Publication


Bibliography  

•    Summary: 125+ publications including 1 book, 6 book chapters, and another book in contract (stand alone, not edited), 2 patents
•    Published Journal papers have ~4200 citations, 12 papers at 100+ citations, h index 33
•    125+ invited/keynote talks

J:  Published/Accepted Journal
P:  Preprint/Submitted
C:  Invited Conference Paper
I:   Invention Disclosure/Patent
B: Book Chapter/Book
T:  Talk

Magnetism and Memory Technology

J1.    “Remarkable tunability in high-frequency magnetoelectric voltage tunable inductor with anisotropy cancellation”,Yongke Yan, Liwei Geng, Yaohua Tan, Jianhua Ma, Avik W. Ghosh, Yu Wang and Shashank Priya, Nature Comms 9, 4998 (2018).

P2.     “Structural and Magnetic Properties Analyses of the Bulk FexCo1­xTiSb alloy system: The Fe0.5Co0.5TiSb Compound as Prototypical Half Heusler”, N. Naghibolashrafi, S. Keshavarz, V.I.Hegde, S. Naghavi, J.Ma, A. Gupta, P. LeClair, W.H. Butler, C.Wolverton, K. Munira, D.Mazumdar, A. W. Ghosh, Submitted

J3.    “Hexagonal Fe2MnGe: Novel Candidate for Perpendicular Magnetic Anisotropy”, Keshavarz, N. Naghibolashrafi, J. Ma, D. Mazumdar, R.Mishra, A. W. Ghosh, W.H. Butler, A. Gupta, C. Mewes, P. LeClair, Submitted.

P4.    “Skyrmion Formation Induced by Antiferromagnetic-enhanced Interfacial Dzyaloshinskii Moriya Interaction”, Marco Chung Ting Ma, Yunkun Xie, Howard Sheng, S. Joseph Poon, and Avik W. Ghosh, arXiv preprint arXiv:1806.06334, 2018
J5.    “Computational Investigation of Inverse­Heusler Compounds for Spintronics Applications”, Jianhua Ma, Jiangang He, Dipanjan Mazumdar, Kamaram Munira, Sahar Keshavarz, Tim Lovorn, C Wolverton, Avik W Ghosh, William H Butler, Phys. Rev. B 98, 094410 (2018).
J6.     “From materials to systems: a multiscale analysis of nanomagnetic switching”, Yunkun Xie, Jianhua Ma, Samiran Ganguly and Avik W. Ghosh, invited paper for J. Comp. Electronics, 16, 1201 (2017).
J7.      “Fokker-Planck Study of Parameter Dependence on Write Error Slope in Spin-Torque Switching, Yunkun Xie, Behtash Behin-Aein, Avik W. Ghosh, IEEE Transactions on Electron Devices, 64, 319 (2017).
J8.      “Computational Investigation of Half-Heusler Compounds for Spintronics Applications”, Jianhua Ma, Vinay I. Hegde, Kamaram Munira, Yunkun Xie, Sahar Keshavarz, David T. Mildebrath, C. Wolverton, Avik W. Ghosh, W. H. Butler, Phys. Rev B 95, 024411 (2017). Selected as Editor’s Highlight.
J9.     “Synthesis and characterization of Fe-Ti-Sb intermetallic compounds: discovery of a new Slater-Pauling phase”, N. Naghibolashrafi, S. Keshavarz, V. I. Hegde, A. Gupta, W. H. Butler, J. Romero, K. Munira, P. LeClair, D. Mazumdar, J. Ma, A. W. Ghosh and C. Wolverton, Phys. Rev. B 93, 104424 (2016).
J10.     “Anisotropy in layered half-metallic Heusler alloy superlattices”, J. G. Azdani, K. Munira, J. Romero, J. Ma, C. Sivakumar, A. W. Ghosh and W. H. Butler, J. Appl. Phys. 119, 043904 (2016).
B11.         “Spin Transfer Torque: A Multiscale Picture”, Y. Xie, K. Munira, I. Rungger, M. T. Stemanova, S. Sanvito and A.W. Ghosh, (invited book chapter, ‘Nanomagnetic and Spintronic Devices for Energy Efficient Memory and Computing’, ed. S. Bandyopadhyay and J. Atulasimha, 2016)
J12.    “Reducing error rates in straintronic multiferroic dipole-coupled nanomagnetic logic by pulse shaping”, K. Munira, Y. Xie, S. Nadri, M. B. Forgues, M. S. Fashami, J. Atulasimha, S. Bandyopadhyay and A. W. Ghosh, Nanotechnology, 26, 245202 (2015).
J13.    “Chiral tunneling of topological states for giant longitudinal spin Hall angle”, K. M. Masum Habib, R. N. Sajjad and A. W. Ghosh, Phys. Rev. Lett. 114, 176801 (2015).
J14.    “Switching of dipole coupled multiferroic nanomagnets in the presence of thermal noise: reliability analysis of hybrid spintronic-straintronic nanomagnetic logic”, S.  Fashami, K. Munira, S. Bandyopadhyay, A W Ghosh and J Atulasimha, IEEE TNano, 12, pp 1206-1212 (2013)
B15.    “Material Issues for efficient Spin-transfer Torque RAMs”, K. Munira, W. A. Soffa and A. W. Ghosh, Chapter 67, pp 849-863, Nanoelectronic Device Applications, CRC Press 2013, ed. James E. Morris, Krzysztof Iniewski.
J16.    “A quasi-analytical model for energy-delay-reliability tradeoff studies in single barrier, perpendicular STT-RAM cell”, K. Munira, W. H. Butler and A. W. Ghosh, IEEE Transactions on Electron Devices Vol. 59, pp 2221-2226 (2012)
J17.     “Advances and Future Prospects of STT-RAM”, E. Chen, D. Apalkov, Z. Diao, A. Driskill-Smith, D. Druist, D. Lottis, V. Nikitin, X. Tang, S. Watts, S. Wang, S. A. Wolf, A. W. Ghosh, J. W. Lu, S. J. Poon, M. Stan, W. H. Butler, S. Gupta, C. K. A. Mewes, T. Mewes and P. B. Visscher, IEEE Trans. Magn. 46, 1873-1878 (2010).

Two-Dimensional Materials

P18.    X. Li, J. Zhang, A. A. Puretzky, A. Yoshimura, X. Sang, O. Cui, Y. Li, A. Oyedele, L. Liang, A. W. Ghosh, V. Meunier, H. Zhao, R. R. Unocic, C. M. Rouleau, B. G. Sumpter, D. B. Geohegan and K. Xiao, “Isotopically enriched two-dimensional MoS2 atomic layers with enhanced in-plane thermal conductivity”, Submitted.
P19.    “Impact of non-idealities on chiral switching in graphene Klein tunnel transistors”, Mirza M. Elahi, K. M. Masum Habib, Ke Wang, Gil-Ho Lee, Philip Kim, and Avik W. Ghosh, Submitted.
P20.    “Atomic scale characterization of graphene p-n junctions for electron-optical applications”, Xiaodong Zhou, Alexander Kerelsky, Mirza M. Elahi, Dennis Wang, K. M. Masum Habib, Redwan N. Sajjad, Pratik Agnihotri, Ji Ung Lee, Avik W. Ghosh, Frances M. Ross, and Abhay N. Pasupathy, Submitted.
P21.    “Graphene Transistor Based on Tunable Dirac-Fermion-Optics”, K Wang, M. M. Elahi, K. M. M. Habib, T. Taniguchi, K. Watanabe, A. W. Ghosh, G-H. Lee, and P. Kim, PNAS 116, 6575 (2019).
J22.    “PdSe2: Pentagonal 2D layers with High Air Stability for Electronics”, A. D. Oyedele, S. Yang, L. Liang, A. A. Puretzky, K. Wang, J. Zhang, P. Yu, P.R. Pudasaini, A. W. Ghosh, Z. Liu, C. M. Rouleau, B. G. Sumpter, M. F. Chisholm, W. Zhou, P. D. Rack, D. B. Geohegan and K. Xiao, JACS 139, 14090 (2017).
J23.    “Spintronic signatures of Klein tunneling in topological insulators”, Yunkun Xie, Yaohua Tan and Avik W. Ghosh, Phys Rev B 96, 205151 (2017).
J24.    “Graphene Klein tunnel transistors for high speed analog RF applications”, Yaohua Tan, Mirza M. Elahi, Han-Yu Tsao, K. M. Masum Habib, N. Scott Barker and Avik W. Ghosh, Nature Scientific Reports 7, 9714 (2017).
I25.    “Graphene device including angular split gate”, R. N. Sajjad and A. Ghosh, US Patent 9,570,559 B2 (2017).
I26.    “Extremely large spin hall angle in topological insulator pn junction”, KMM Habib, RN Sajjad, A Ghosh US Patent 9,865,713 (2017).
J27.    “Electron optics with ballistic graphene junctions”, S. Chen, Z. Han, M. M. Elahi, K. M. Masum Habib, L. Wang, B. Wen, Y. Gao, T. Taniguchi, K. Watanabe, J. Hone, A. W. Ghosh and C. R. Dean, Science 353, 1522 (2016). Top-10 breakthrough of 2016, Physics World Editors.
J28.    “Modified Dirac Hamiltonian for Efficient Quantum Mechanical Simulations of Micron Sized Devices", M. Habib, R. Sajjad and A. W. Ghosh, Appl. Phys. Lett., 108, 113105 (2016).
J29.    “Quantum transport at the Dirac point: Mapping out the minimum conductivity from pristine to disordered graphene”, R. N. Sajjad, F. Tseng, M. Habib and A. W. Ghosh, Phys. Rev. B 92, 205408 (2015).
J30.    “Manipulating chiral transmission with gate geometry: switching with graphene with transmission gaps”, R. Sajjad and A. W. Ghosh, ACS Nano 7, 9808, 6pps (2013),
J31.    “Atomistic deconstruction of current flow in graphene based hetero-junctions”, R. N. Sajjad, C. Polanco and A. W. Ghosh, invited paper, Special Issue on graphene nanostructures, Ed. Branislav Nikolic, J. Comp. El, 12, 232- 247 (2013).
J32.    Manifestation of Chiral tunneling in tilted graphene pn junction", R. N. Sajjad, S. Sutar, J. Lee and A. W. Ghosh, Phys. Rev. B 86, 155412 (2012), 5 pps
B33.    “Graphene Nanoribbons: From chemistry to circuits”, F. Tseng, D. Unluer, M. R. Stan and A. W. Ghosh, Chapter 18 pages 555-586, ‘Graphene Nanoelectronics: Metrology, Synthesis, Properties and Applications’, Ed. H. Raza (Springer), 2012
J34.    “High efficiency switching using graphene based electron optics", R. Sajjad and A. W. Ghosh, Appl. Phys. Lett. Vol. 99, 123101, 4pps (2011).
J35.    “Monolithically Patterned Wide-Narrow-Wide All-Graphene Devices”, Dincer Unluer, Frank Tseng, Avik W. Ghosh, Mircea R. Stan, IEEE-TNano, 10, 931-939, (2011).
J36.    “Diluted chirality dependence in edge rough graphene nanoribbon field-effect transistors”, F. Tseng, D. Unluer, K. Holcomb, M. Stan and A. W. Ghosh, Appl. Phys. Lett. 94, 223112, 3pps (2009).

Low Power Logic, Neuromorphic Computing and Switching devices

J37.     “Modeling tunnel field effect transistors - from interface chemistry to non-idealities to circuit level performance”, Sheikh Z. Ahmed, Yaohua Tan, Daniel S. Truesdell, Benton H. Calhoun, Avik W. Ghosh, Journal of Applied Physics, vol. 124, pp. 154503, 2018
C38.     “Hardware based Spatio-Temporal Neural Processing Backend for Imaging Sensors: Towards a Smart Camera”, Samiran Ganguly, Yunfei Gu, Mircea R. Stan, and Avik W. Ghosh, invited paper, SPIE 2018
P39.     “Reservoir computing using stochastic p-bits”, Samiran Ganguly, Kerem Y. Camsari and Avik W. Ghosh, arxiv: 1709.10211 (2017).
P40.     “Steep Subthreshold Switching with Nanomechanical FET Relays”, D. Unluer and A. W. Ghosh, IEEE-TED 63, 1681 (2016).
P41.    “Transmission engineering as a route to subthermal switching”, A. W. Ghosh, special issue on low subthreshold switching, IEEE JEDS 3, 135 (2015).
P42.    “Computing with Nonequilibrium Ratchets”, D. Unluer and A. W. Ghosh, IEEE TNano 12, 330-339 (2013).
B43.    “Emerging Devices”, S. Bandyopadhyay, M. Cahay and A. W. Ghosh, Chapter 5, pps 59-69 in ‘Electron Devices: An Overview by the Technical Area Committee of the IEEE Electron Devices Society’, Ed. Joachim Burghartz, John Wiley & Sons Ltd, 2013. PROSE award 2013.

Phononics and Thermal Transport

P44.    “Boosting thermal conductivity of two-dimensional MoS2 through isotope-engineering”, Xufan Li, Jingjie Zhang, Alexander A. Puretzky, Anthony Yoshimura, Xiahan Sang, Qiannan Cui, Yuanyuan Li, Liangbo Liang, Avik W. Ghosh, Hui Zhao, Raymond R. Unocic, Vincent Meunier, Christopher M. Rouleau, Bobby G. Sumpter, David B. Geohegan, Kai Xiao, submitted to Advanced Materials, 2018
J45.    “Interplay between coherent and incoherent phonon transport in the thermal conductivity of superlattices from the nanoscale to the microscale”, R. Cheaito, C. A. Polanco, S. Addamane, J. Zhang, A. W. Ghosh, G. Balakrishnan and P. E. Hopkins, Phys. Rev. B 97, 085306 (2018).  
J46.    “Optimizing the interfacial thermal conductance at gold-alkane junctions from 'First Principles”, Jingjie Zhang, Carlos A. Polanco, Avik W. Ghosh, ASME Journal of Heat Transfer 140, 092405 (2018).
P47.    “On the wave and particle nature of phonons contributing to thermal transport in superlattices”, Ramez Cheaito, Sadhvikas Addamane, Carlos A. Polanco, Jingjie Zhang, Avik W. Ghosh, Ganesh Balakrishnan, and Patrick E. Hopkins, Submitted
J48.    “Effects of bulk and interfacial anharmonicity on thermal conductance at solid/solid interfaces”, Nam Q. Le, Carlos A. Polanco, Rouzbeh Rastgarkafshgarkolaei, Jingjie Zhang, Avik W. Ghosh, Pamela M. Norris, Phys. Rev. B 95, 245417 (2017).
J49.    “Design rules for interfacial thermal conductance - building better bridges”, Carlos A. Polanco, Rouzbeh Rastgarkafshgarkolaei, Jingjie Zhang, Nam Le, Pamela M. Norris, Avik W. Ghosh, Phys. Rev. B 95, 195303 (2017).
J50.    “Role of crystal structure and junction morphology on interface thermal conductance”, C. A. Polanco, R. Rastgarkafshgarkolaei, J. Zhang, N. Q. Le, P. M. Norris, P. E. Hopkins, and A. W. Ghosh, Phys. Rev. B 92, 144302 (2015).
J51.    “Enhancing Phonon Flow through 1D interfaces by impedance matching”, C. Polanco  and A. W. Ghosh, J. Appl. Phys. 116, 083503 (2014).
J52.    “Impedance matching of atomic thermal interfaces using primitive block decomposition,” C. Polanco, C. B. Saltonstall, P. M. Norris, P. E. Hopkins, and A.W. Ghosh, Cover article, Nanoscale and Microscale Thermophysical Engineering, 17, 263-279 (2013).
J53.    “Effect of interface adhesion and impurity mass on phonon transport at atomic junctions,” C. B. Saltonstall, C. Polanco, J. C. Duda, A. W. Ghosh, P. M. Norris, and P.E. Hopkins, Journal of Applied Physics 113, 013516, 8pps (2013).
J54.    “Extracting phonon thermal conductance across nanoscale junctions: Non-equilibrium Green's function approach compared to semiclassical methods", P. E. Hopkins, P. M. Norris, M. Tsegaye and A. W. Ghosh, Journal of Applied Physics 106, 063503, 10pps (2009).
J55.    “Phonon runaway in nanotube quantum dots”, L. Siddiqui, A. W. Ghosh and S. Datta, Phys. Rev. B 75, 085433, 9pps (2007).

Organic Molecules, Nanowires/Nanotubes and Quantum Dots

J56.    "Using room temperature current noise to characterize single molecular spectra", S. Vasudevan and A. W. Ghosh, ACS Nano 8, 2111-2117 (2013).
B57.    Electronics with Molecules”, A. W. Ghosh, Invited Book Chapter In Bhattacharya P. Fornari R, and Kamimura H (eds) Comprehensive Semiconductor Science and Technology, vol. 5, pp. 383-479 (2011), Amsterdam: Elsevier.
J58.    "Coupling electrical and optical gating for electronic read-out of quantum dot dynamics", S. Vasudevan, K. Walczak and A. W. Ghosh, Phys. Rev. B 82, 085324, 5pps (2010).
J59.    "Controlling transistor threshold voltages using molecular dipoles", S. Vasudevan, N. Kapur, T. He, M. Neurock, J. M. Tour and A. W. Ghosh, J. Appl. Phys. 105, 093703, 4pps (2009).
J60.    “Reversal of current blockade through multiple trap correlations”, J. Chan, B. Burke, K. Evans, K. A. Williams, S. Vasudevan, M. Liu, J. Campbell and A. W. Ghosh, Physical Review B 80, 033402, 4pps (2009).
J61.    “The role of Many Particle Excitations in Coulomb Blockaded Transport”, B. Muralidharan, L. Siddiqui and A. W. Ghosh, J. Phys. Cond. Mat. 20, 374109, 13pps (2008).
J62.    “Rectification by charging -- Contact-induced current asymmetry in Coulomb Blockaded molecules”, O. D. Miller, B. Muralidharan, N. Kapur and A. W. Ghosh, Phys. Rev. B, 77, 125427, 10pps (2008).
J63.    “Modeling electrostatic and quantum detection of molecules”, S. Vasudevan, K. Walczak, N. Kapur, M. Neurock and A. W. Ghosh, IEEE-Sensors Vol. 8, 857, 4pps (2008).
J64.    “Impact of structure relaxation on the Performance of small Diameter, n-type <110> Si-Nanowire FETs”, G-C. Liang, D. Kienle, S. Patil, J. Wang, A. W. Ghosh and S. Khare, IEEE-TNano 6, 225, 5pps (2007).
J65.    “Theory of high bias Coulomb Blockade in ultrashort molecules”, B Muralidharan, A. W. Ghosh, S. K. Pati and S. Datta, IEEE-TNT 6, 536, 9pps (2007).
J66.    “Conductance in molecular quantum dots – fingerprints of wave-particle duality?”, B. Muralidharan, A. W. Ghosh and S. Datta, Molecular Simulation (Special Issue ed. D. Beratan), 32, 751-758 (2006).
J67.    “Probing electronic excitations in molecular conduction”, B. Muralidharan, A. W. Ghosh and S. Datta, Phys. Rev. B 73, 155410, 5pps (2006).
J68.    “Atomistic Modeling of Metal-nanotube contacts”, D. Kienle, A. Ghosh and M. Lundstrom, J. Comp. El. 4, 97-100 (2005).
J69.    “A self-consistent transport model for molecular conductors with applications to some real systems”, F. Zahid, M. Paulsson, E. Polizzi, A. W. Ghosh and S. Datta, J. Chem. Phys. 123, 064707, 10pps (2005).
J70.    “On the validity of the Parabolic Effective-Mass approximation for the current-voltage calculation of silicon nanowire transistors”, J. Wang, A. Rahman, A. Ghosh, G. Klimeck and M. Lundstrom, IEEE Transactions on Electron Devices 52, 1589, 5pps (2005).
J71.    “Theoretical Investigation of surface roughness scattering in silicon nanowire transistors”, J. Wang, E. Polizzi, A. Ghosh, S. Datta and M. Lundstrom, Appl. Phys. Lett. 87, 043101, 3pps (2005).
J72.    “Performance evaluation of ballistic nanowire transistors with atomic-basis dispersion relations”, J. Wang, A. Rahman, A. Ghosh, G. Klimeck and M. Lundstrom, Appl. Phys. Lett. 86, 093113, 3pps (2005).
J73.    “A Quantum Mechanical Approach for the Simulation of Si/SiO2 interface roughness scattering in Silicon Nanowire Transistors”, J. Wang, E. Polizzi, A. Ghosh, S. Datta and M. Lundstrom, J. Comp. El. 4, 453-457 (2005).
J74.    “Identifying contact effects in electronic conduction through buckyballs on silicon”, G-C. Liang, A. W. Ghosh and S. Datta, Phys. Rev. Lett. 95, 076403, 4pps (2005).
J75.    “Molecules on silicon: Self-consistent First-Principles Theory and calibration to experiments”, T. Rakshit, G-C. Liang, A. W. Ghosh, M. C. Hersam and S. Datta, Phys. Rev. B 72, 125305, 11pps (2005).
J76.    “Modeling Challenges in Molecular Electronics on Silicon”, T. Rakshit, G-C. Liang, A. W. Ghosh and S. Datta, J. Comp. El. 4, 83-86 (2005).
J77.    “Silicon-based molecular electronics”, T. Rakshit, G-C. Liang, A. W. Ghosh and S. Datta, Nano Lett. 4, 1803, 5pps (2004).
J78.    “Electrostatic potential profiles of molecular conductors”, G-C. Liang, A. W. Ghosh, M. Paulsson and S. Datta, Phys. Rev. B 69, 115302, 12pps (2004).
B79.    “Molecular Electronics: Theory and Device prospects”, A. W. Ghosh, P. S. Damle, S. Datta and A. Nitzan, MRS Bull. 29, 391, 5pps (2004) (Special issue on Molecular Transport Junctions).
J80.    “Charging-induced asymmetry in molecular conductors”, F. Zahid, A. W. Ghosh, M. Paulsson, E. Polizzi and S. Datta, Phys. Rev. B 24, 245317, 5pps (2004).
J81.    “Gating of molecular transistors: electrostatic and conformational”, A. W. Ghosh, T. Rakshit and S. Datta, Nano Lett. 4, 565, 4pps (2004), adopted for a course at MIT.  
J82.    “Breaking of general rotational symmetries by multidimensional classical ratchets”, A. W. Ghosh and S. V. Khare, Phys. Rev. E 67, 056110, 11pps (2003).
J83.    “Molecular conduction: paradigms and possibilities”, A. W. Ghosh and S. Datta, J. Comp. El. 1, 515, 11pps (2002).
J84.    “First-Principles Analysis of Molecular Conduction Using Quantum Chemistry Software”, P. S. Damle, A. W. Ghosh and S. Datta, Chem. Phys. 281, 171-187 (2002) (Special issue on Molecular Nanoelectronics, Ed. Mark Ratner).
J85.    “Charge transfer in molecular conductors - oxidation or reduction?”, A. W. Ghosh, F. Zahid, S. Datta and R. Birge, Chem. Phys. 281, 225-230 (2002) (Special issue on Molecular Nanoelectronics, Ed. Mark Ratner).
J86.    “Unified description of molecular conduction: from molecules to metallic wires”, P. S. Damle, A. W. Ghosh and S. Datta, Phys. Rev. B 64 Rapid Comms., 201403 (R), 4pps (2001).
J87.    “Temperature dependence of the conductance of multi-walled carbon nanotubes”, E. Graugnard, B. Walsh, A. W. Ghosh, S. Datta, P. J. de Pablo and R. Reifenberger, Phys. Rev. B 64, 125407, 7pps (2001)

Transport Formalism and Computational Methods

P88.    “Machine Learning Electron Correlation in Disordered Medium”, Jianhua Ma, Yaohua Tan, Avik W. Ghosh and Gia-Wei Chern, arXiv:1810.02323
B89.    “Nanoelectronics, a Molecular View” – Avik Ghosh, World Scientific Series in Nanoscience and Nanotechnology, 2016.
J90.    “First principles study and empirical parametrization of twisted bilayer MoS2 based on band-unfolding”, Y. Tan, F. Chen and A. W. Ghosh, Applied Physics Letters, 109, 101601 (2016).
B91.    “Nanoscale device modeling”, P. S. Damle, A. W. Ghosh and S. Datta, Book chapter in “Molecular Nanoelectronics”, 21pps, Ed. Mark Reed and Takhee Lee, American Scientific Publishers, 2003.
J92.    “Extended Huckel theory for bandstructure, chemistry and transport.  Part II: Silicon”, D. Kienle, K. Bevan, G-C. Liang, L. Siddiqui, J-I. Cerda and A. W. Ghosh, J. Appl. Phys. 100, 043715, 8pps (2006).
J93.    “Extended Huckel theory for bandstructure, chemistry and transport. Part I: Carbon Nanotubes”, D. Kienle, J-I. Cerda and A. W. Ghosh, J. Appl. Phys. 100, 043714, 9pps (2006).
J94.    “Generalized effective mass approach for cubic semiconductor n-MOSFETs on arbitrarily oriented wafers”, A. Rahman, A. Ghosh and M. Lundstrom, J. Appl. Phys. 97-100, 053702, 12pps (2005).
J95.    “Rotation in an asymmetric multidimensional potential in the presence of colored noise”, A. W. Ghosh and S. V. Khare, Phys. Rev. Lett. 84, 5243, 4pps (2000).

Chemical Sensors, Photo Detectors and THz response

J96. “Toward deterministic construction of low noise avalanche photodetector materials”, A. K. Rockwell, M. Ren, M. Woodson, A. H. Jones, S. D. March, Y. Tan, Y. Yuan, Y. Sun, R. Hool, S. J. Maddox, M. L. Lee, A. W. Ghosh, J. C. Campbell, and S. R. Bank, Applied Physics Letters, vol. 113, pp. 102106, 2018
J97.    Temperature dependence of the ionization coefficients of InAlAs and AlGaAs digital alloys Yuan Yuan, Jiyuan Zheng, Yaohua Tan, Yiwei Peng, Ann-Kathryn Rockwell, Seth R Bank, Avik Ghosh, Joe C Campbell, Photonics Research 6, 794 (2018).
J98.    “Digital Alloy InAlAs Avalanche Photodiodes”, Jiyuan Zheng, Yuan Yuan, Yaohua Tan, Yiwei Peng, Ann-Kathrine Rockwell, Seth R Bank, Avik Ghosh, Joe C Campbell, Journal of Lightwave Technology, 36, 3580 (2018).
J99.    “Bloch oscillations in the presence of plasmons and phonons”, A. W. Ghosh, L. Jönsson and J. W. Wilkins, Phys. Rev. Lett. 85, 1084, 4pps (2000).
J100.    “Coupled Bloch-phonon oscillations in GaAs/AlGaAs superlattices: theory and experiment”, T. Dekorsy, A. Bartels, H. Kurz, A. W. Ghosh, L. Jönsson, J. W. Wilkins, K. Kohler, R. Hey and K. Ploog, Physica E 7, 279-284 (2000).
J101.    “Nonlinear Terahertz response of a one dimensional superlattice,” A. W. Ghosh and J. W. Wilkins, Phys. Rev. B 61, 5423, 8pps (2000).
J102.    “Third harmonic generation by Bloch oscillating electrons in a quasi-optical array,” A. W. Ghosh, M. C. Wanke, S. J. Allen and J. W. Wilkins, Appl. Phys. Lett. 74, 2164, 3pps (1999).
J103.    “Reflection of THz radiation by a superlattice,” A. W. Ghosh, A. V. Kuznetsov and J. W. Wilkins, Phys. Rev. Lett.  79, 3494, 4pps (1997).
J104.     “Diffusion rate for a Brownian particle in a cosine potential in the presence of colored noise,” A. Ghosh, Phys. Lett. A 187, 54-58 (1994).

Other Conference Publications

C105.    “APD Performance Enhancement: Minigap Engineering in Digital Alloys”, Sheikh Z. Ahmed, Yaohua Tan, Jiyuan Zheng, Joe C. Campbell, and Avik W. Ghosh, IEEE Photonics Conference, 2018
C106.    Jianhua Ma, Jiangang He, Vinay I. Hegde, Kamaram Munira, Nariman  Naghibolashrafi, Sahar Keshavarz, Dipanjan Mazumdar, Avik W. Ghosh, C. Wolverton and W. H. Butler. (2017)
C107.    Computational Investigation of Heusler Compounds for Spintronics Applications. AVS 64th International Symposium & Exhibition, Tampa Convention Center, Tampa, Florida, USA.
C108.    Jianhua Ma, Jiangang He, Dipanjan Mazumdar, Kamaram Munira, Sahar Keshavarz, Tim Lovorn, C Wolverton, Avik W Ghosh, William H Butler. (2017). Computational Investigation of Inverse­Heusler Compounds for Spintronics Applications. 62nd Annual Conference on Magnetism and Magnetic Materials (2017 MMM), The David L. Lawrence Convention Center, Pittsburgh, PA, USA.
C109.    “Computational Investigation of Heusler Alloys for Spintronic Applications”, Jianhua Ma, Vinay I. Hegde, Kamaram Munira, Yunkun Xie, Sahar Keshavarz, C. Wolverton, Avik W. Ghosh and William H. Butler, Annual Conference on Magnetism and Magnetic Materials, 2016.
C110.    “Current saturation and steep switching in graphene PN junctions using angle-dependent scattering”, M. M. Elahi and A. W. Ghosh, 74th Device Research Conference, Delaware 2016.
C111.    “First principles study of twisted bilayer MoS2 through band unfolding”, Y. Tan and A. W. Ghosh, 74th Device Research Conference, Delaware 2016.
C112.    “Fokker-Planck simulation of stochastic write error in spin torque switching with thermal noise”, Y. Xie, B. Behin-Aein and A. W. Ghosh, 74th Device Research Conference, Delaware 2016.
C113.    "A quantum mechanics inspired simulation platform for nanoscale devices", Redwan N. Sajjad, K. M. Masum Habib, Avik Ghosh, SRC TECHCON, Austin, 2014.
C114.    “Conductance of graphene: role of metal contact, charge puddles and differential gating”, Redwan N. Sajjad, Frank Tseng, Avik Ghosh, 72st Device Research Conference, Santa Barbara, 2014.
C115.    “Novel switching mechanism through angle dependent transmission in graphene pn junction”, Redwan N. Sajjad, Avik Ghosh, 71st Device Research Conference, Notre Dame, 2013.
C116.    "Novel switching mechanism with graphene pn junctions: device physics and circuit analysis", Redwan N. Sajjad, Chenyun Pan, Azad Naeemi, Avik Ghosh, SRC TECHCON, Ausin, 2013.
C117.    “Balancing stress & dipolar interactions for fast, low power, reliable switching in multiferroic logic”, K. Munira, S. Nadri, M. Forgues, A. W. Ghosh, Device Research Conference, 67-68, 2012.
C118.    “Modeling and visualizing electrons in graphene”, Redwan N. Sajjad, F. Tseng, Avik Ghosh, 15th International Workshop on Computational Electronics (IWCE), Madison, 2012.
C119.    “Graphene electronics and electron optics: quantum transport and device opportunities”, Redwan N. Sajjad, F. Tseng, D. Unluer, Avik Ghosh, Graphene International Conference, Belgium, 2012.
C120.    “Thermal Impedance Matching at Nanoscale Material Interfaces”, C. A. Polanco, C. B. Saltonstall, P. E. Hopkins, P. M. Norris and A. W. Ghosh,
ASME Summer Heat Transfer Conference, 2012
C121.    “Tunable transmission gap in graphene p-n junction”, Redwan N. Sajjad and Avik Ghosh, International Semiconductor Device Research Symposium (ISDRS), Maryland, 2011.
C122.    “Comparative material issues for fast reliable switching in STT-RAMs”, K. Munira, W.A. Soffa, A.W. Ghosh, 11th IEEE Conference on Nanotechnology (IEEE-NANO), pp.1403-1408, Aug. 2011.
C123.    “Molecular Spectroscopy from current fluctuations”, S. Vasudevan, T. W. Chan, K. Williams and A. W. Ghosh, Villa Conference on Interaction among Nanostructures, 2010, Santorini, Greece.
C124.    “A molecular description of current flow”, A. W. Ghosh, K. Munira and M. Tsegaye, NanoTurkey 2010.
C125.    “Beyond CMOS switching paradigms”, L. Li, D. Unluer, M. R. Stan and A. W. Ghosh, IEEE-Nano 2010, South Korea.
C126.    Self-consistent Parametrized Physical MTJ Compact Model for STT-RAM”, A. Nigam, K. Munira, A. Ghosh, S. Wolf, E. Chen and M. R. Stan, CAS 2010.
C127.    “Model based study on performance and energy optimization for STT-RAM”, A. Nigam, K. Munira, A. W. Ghosh, S. Wolf and M. R. Stan, Non Volatile Memory Workshop 2010.
C128.    “Graphene Devices, Interconnect and Circuits -- Challenges and Opportunities”, Mircea R. Stan, Dincer Unluer, Avik Ghosh and Frank Tseng, ISCAS 2009.
C129.    “Assumptions of local equilibrium in thermal boundary conductance calculations”, P. E. Hopkins, M. S. Tsegaye, P. M. Norris and A. Ghosh, Proceedings of MNHT2008: 2008 ASME Micro/Nanoscale Heat Transfer International Conference, Tainan, Taiwan.  
C130.    “Are short molecules quantum dot arrays” – B. Muralidharan, A. W. Ghosh, S. K. Pati, S. Datta, 6th IEEE Conference on Nanotechnology, 2006, pages 419-421.
C131.    “Using trap-assisted tunneling for molecular sensing?”, A. W. Ghosh, Best Paper Award at ISSSR 2006 for Frontier Sensing and Monitoring.
C132.    “Molecular elements on silicon substrates: modeling issues and device prospects”
A. W. Ghosh, G. C. Liang, T. Rakshit, D. Kienle and S. Datta, 4th IEEE Conference on Nanotechnology, 2004, pages 276.
C133.    “Effective Mass Approach for n-MOSFETs on arbitrarily oriented wafers”, A. Rahman, M. Lundstrom and A. W. Ghosh, 10th International Workshop on Computational Electronics, IWCE-10, 2004, pages 177-178.
C134.    “Huckel I-V 3.0: a self-consistent model for molecular transport and its applications”, F. Zahid, M. Paulsson, E. Polizzi, A. W. Ghosh, L. Siddiqui and S. Datta, 10th International Workshop on Computational Electronics, IWCE-10, 2004, pages 102
C135.    “Assessment of Ge n-MOSFETs by quantum simulation”, A. Rahman, A. Ghosh and M. Lundstrom, IEDM Tech. Dig. p. 19.4, 4pps (2003).
C136.    “Coupled Bloch-phonon modes in superlattices”, A. W. Ghosh, L. Jonsson, J. W. Wilkins, T. Dekorsy, A. Bartels, H. Kurz, K. Kohler, R. Hey and K. Ploog, 2001 Quantum Electronics and Laser Science Conference (QELS ’01), pages 150-151.
C137. “A Multiscale Materials-to-Systems Modeling of Polycrystalline Pb-Salt Photodetectors”, Samiran Ganguly, Moonhyung Jang, Yaohua Tan, Sung-Shik Yoo, Mool C. Gupta, Avik W. Ghosh, arXiv:1806.02933

Preprint

  • P1. Computing and Memory Technologies based on Magnetic Skyrmions (2021)

    Hamed Vakili, Wei Zhou, Chung T Ma, Md Golam Morshed, Mohammad Nazmus Sakib, Tim Hartnett, Jun-Wen Xu, Kai Litzius, Yassine Quessab, Prasanna Balachandran, Mircea Stan, S J Poon, Andrew D. Kent, Geoffrey Beach, and Avik W. Ghosh


    Solitonic magnetic excitations such as domain walls and, specifically, skyrmionics enable the possibility of compact, high density, ultrafast, all-electronic, low-energy devices, which is the basis for the emerging area of skyrmionics. The topological winding of skyrmion spins affects their overall lifetime, energetics and dynamical behavior. In this review, we discuss skyrmionics in the context of the present day solid state memory landscape, and show how their size, stability and mobility can be controlled by material engineering, as well as how they can be nucleated and detected. Ferrimagnets near their compensation points are important candidates for this application, leading to detailed exploration of amorphous CoGd as well as the study of emergent materials such as Mn4N and Inverse Heusler alloys. Along with material properties, geometrical parameters such as film thickness, defect density and notches can be used to tune skyrmion properties, such as their size and stability. Topology, however, can be a double-edged sword, especially for isolated metastable skyrmions, as it brings stability at the cost of additional damping and deflective Magnus forces compared to domain walls. Skyrmion deformation in response to forces also makes them intrinsically slower than domain walls. We explore potential analog applications of skyrmions, including temporal memory at low density - one skyrmion per racetrack - that capitalizes on their near ballistic current-velocity relation to map temporal data to spatial data, and decorrelators for stochastic computing at higher density that capitalizes on their interactions. We summarize the main challenges to achieve a skyrmionics technology, including maintaining positional stability with very high accuracy, electrical readout, especially for small ferrimagnetic skyrmions, deterministic nucleation and annihilation and overall integration with digital circuits with the associated circuit overhead.

    Link
  • P2. Tuning Dzyaloshinskii-Moriya Interaction in Ferrimagnetic GdCo: A First Principles Approach (2021)

    MG. Morshed, KH. Khoo, Y. Quessab, J. Xu, R. Laskowski, P. V. Balachandran, A. D. Kent, and A. W. Ghosh


    We present a systematic analysis of our ability to tune chiral Dzyaloshinskii-Moriya Interactions (DMI) in compensated ferrimagnetic Pt/GdCo/Pt1−xWx trilayers by cap layer composition. Using first principles calculations, we show that the DMI increases rapidly for only ∼ 10% W and saturates thereafter, in agreement with experiments. The calculated DMI shows a spread in values around the experimental mean, depending on the atomic configuration of the cap layer interface. The saturation is attributed to the vanishing of spin orbit coupling energy at the cap layer and the simultaneous constancy at the bottom interface. Additionally, we predict the DMI in Pt/GdCo/X (X = Ta, W, Ir) and find that W in the cap layer favors a higher DMI than Ta and Ir that can be attributed to the difference in d-band alignment around the Fermi level. Our results open up exciting combinatorial possibilities for controlling the DMI in ferrimagnets towards nucleating and manipulating ultrasmall high-speed skyrmions.

    Link

Nanomagnetism

  • J1. Self-focusing hybrid skyrmions in spatially varying canted ferromagnetic systems, PRB (2020)

    H Vakili, Y Xie, and A W Ghosh


    Magnetic skyrmions are quasiparticle configurations in a magnetic film that can act as information carrying bits for ultrasmall, all-electronic nonvolatile memory. The skyrmions can be nucleated and driven by spin-orbit torque from a current driven in a heavy metal underlayer. Along its gyrotropic path, a Magnus force can cause a skyrmion to be annihilated at the boundaries. By combining interfacial and bulk Dzyaloshinskii-Moriya interactions (DMIs), for instance by using a B20 material on top of a heavy metal layer with high spin-orbit coupling, it is possible to engineer a hybrid skyrmion that will travel parallel to the racetrack with zero Magnus force. We show that by using a spatially varying interfacial DMI, a hybrid skyrmion will automatically self-focus onto such a track as its domain angle evolves along the path. Furthermore, using a gate driven voltage controlled magnetic anisotropy, we can control the trajectory of the hybrid skyrmion and its eventual convergence path and lane selection in a racetrack geometry.

    Link
  • J2. Temporal Memory with Magnetic Racetracks, JXCDC (2020)

    Hamed Vakili, Mohammad Nazmus Sakib, Samiran Ganguly, Mircea Stan, Matthew W Daniels, Advait Madhavan, Mark D Stiles, and Avik W Ghosh


    Race logic is a relative timing code that represents information in a wavefront of digital edges on a set of wires in order to accelerate dynamic programming and machine learning algorithms. Skyrmions, bubbles, and domain walls are mobile magnetic configurations (solitons) with applications for Boolean data storage. We propose to use current-induced displacement of these solitons on magnetic racetracks as a native temporal memory for race logic computing. Locally synchronized racetracks can spatially store relative timings of digital edges and provide non-destructive read-out. The linear kinematics of skyrmion motion, the tunability and low-voltage asynchronous operation of the proposed device, and the elimination of any need for constant skyrmion nucleation and annihilation make these magnetic racetracks a natural memory for low-power, highthroughput race logic applications.

    Link
  • C1. Magnetic skyrmion-based programmable hardware, Spintronics XIII (2020)

    MN Sakib, H Vakili, S Ganguly, S Mosanu, A W Ghosh, and M Stan


    Magnetic skyrmions are quasiparticle configurations in a magnetic film that can act as information carrying bits for ultrasmall, low power nonvolatile memory. Skyrmions can be nucleated and driven by spin-orbit torque from a current driven in a heavy metal underlying a ferromagnetic layer, the configuration commonly called a racetrack. Recently it has been shown that by hybridizing the skyrmion between Neel and Bloch types the magnus effect on skyrmion motion, which makes it veer from a straight path down a racetrack, can be effectively canceled which provides them a self-focused naturally converging lane" to travel through. This is achieved by exploiting the voltage controlled magnetic anisotropy effect whereby the magnetic anisotropy of the ferromagnetic racetrack can be positionally modulated by a gate voltage. In this work we show, using detailed micromagnetic simulations, that by using hybrid skyrmions we can obtain demultiplexer functionality out of a racetrack. We further propose a hybrid skyrmionic reconfigureable computing fabric. In conventional CMOS based field programmable gate arrays, SRAM cells are used to build a LUTs storing pre-computed truth-table of a Boolean function and a multiplexer selects one of the storage cells as the output. We show that non-volatile hybrid skyrmions can also act as the memory element and the gateable self-focused nature of the hybrid skyrmions can be exploited to program the proposed CMOS-skyrmion hybrid design to perform different logic operations. The low driving energy and non-volatility of magnetic skyrmion in a racetrack promises the development of energy efficient programmable architecture for future system-on-a-Chip (SoC) designs.

    Link
  • J3. Computational Search for Ultrasmall and Fast Skyrmions in the Inverse Heusler Family, IEEE Trans. on Mag. (2020)

    Yunkun Xie, Jianhua Ma, Hamed Vakilitaleghani, Yaohua Tan, and Avik W Ghosh


    Skyrmions are magnetic excitations that are potentially ultrasmall and topologically protected, thus making them interesting for high-density all-electronic ultrafast storage applications. While recent experiments have confirmed the existence of various types of skyrmions, their typical sizes are much larger than traditional domain walls, except at very low temperature. In this article, we explore the optimal material parameters for hosting ultrasmall, fast, and room temperature stable, isolated Neel (hedgehog) skyrmions. As concrete examples, we explore potential candidates from the inverse Heusler family. Using first-principles calculations of structural and magnetic properties, we identify several promising ferrimagnetic inverse Heusler half-metal/near half-metals and analyze their phase space for size and metastability.

    Link

Beyond CMOS Logic

  • J1. Minimum-Energy Digital Computing with Steep Subthreshold Swing Tunnel FETs (2020)

    Daniel S. Truesdell, Sheikh Z. Ahmed, Avik W. Ghosh, and Benton H. Calhoun


    Energy efficiency in digital circuits is limited by the subthreshold swing (SS), which defines how abruptly a transistor switches between its on and off-states. The SS is particularly important for circuits targeting minimum-energy computation which operate in the subthreshold region between the on and off-states of the transistor. The SS of MOSFET devices is fundamentally limited by thermionic emission, which has inspired a search for new devices whose SS can reach below the Boltzmann thermal limit. Tunnel field-effect transistors (TFETs) have emerged as a post-CMOS candidate with low (steep) SS and have been investigated using an evolving selection of geometries and materials that yield continuously improving device performance and circuit performance estimates. To unify previous works and guide future TFET iterations, this paper provides a comprehensive theory on minimum-energy operation in the subthreshold region for steep-SS devices. We show that the optimal supply voltage for energy minimization and minimum obtainable energy are both proportional to the SS, and that a fundamental limit exists for the required Ion/Ioff to achieve operation at the minimum-energy point. We explore how device knobs affect the optimization space for minimum-energy operation, and analyze how common TFET non-idealities affect the potential for minimum-energy operation.

    Link

Photodetectors

  • J1. Extrinsic voltage control of effective carrier lifetime in polycrystalline PbSe mid-wave IR photodetectors for increased detectivity, AIP Advs (2020)

    Samiran Ganguly, Xin Tang, Sung-Shik Yoo, Philippe Guyot-Sionnest, and Avik W. Ghosh


    Polycrystalline PbSe for mid-wave infrared (IR) photodetectors is an attractive material option due to its high operating/ambient temperature operation and relatively easy and cheap fabrication process, making it a candidate for low-power, small footprint, uncooled/passively cooled photodetectors. However, there are many material challenges that reduce the specific detectivity (D*) of these detectors. In this work, we demonstrate that it is possible to improve upon this metric by externally modulating the effective lifetime of conducting carriers by application of a back-gate voltage that can control the recombination rate of carriers in the detector by increasing the passivation of PbSe. We build a back-gated PbSe detector, in which we experimentally observe unambiguous signature of effective carrier modulation with a back-gate voltage for different temperatures. We develop a quantitative model for the detector that captures and closely benchmarks this modulation, which is then used to project the increase in D* in better optimized detector designs. This approach when combined with other techniques, such as plasmonic enhancement of light absorption, can lead to substantive enhancement of performance in PbSe mid-wave IR detectors widening their application space.

    Link
  • C1. Development of high-performance graphene-HgCdTe detector technology for Mid-wave Infrared Applications, SPIE (2020)

    Ashok K. Sood, John W. Zeller, Parminder Ghuman, Sachidananda Babu, Nibir K. Dhar, Samiran Ganguly, Avik Ghosh


    High performance detector technology is being developed for sensing over the mid-wave infrared (MWIR) band for NASA Earth Science, defense, and commercial applications. The graphene-based HgCdTe detector technology involves the integration of graphene with HgCdTe photodetectors that combines the best of both materials, and allows for higher MWIR (2-5 μm) detection performance compared with photodetectors using only HgCdTe material. The interfacial barriers between the HgCdTe-based absorber and the graphene act as a tunable rectifier that reduces the recombination of photogenerated carriers in the detector. The graphene layer also acts as high mobility channel that whisks away carriers before they recombine, further enhancing detection performance. This makes them much more practical and useful for MWIR sensing applications such as remote sensing and earth observation, e.g., in smaller satellite platforms (CubeSat) for measurement of thermal dynamics with better spatial resolution. The objective of this work is to demonstrate graphene-based HgCdTe room temperature MWIR detectors and arrays through modeling, material development, and device optimization. The primary driver for this technology development is the enablement of a scalable, low cost, low power, and small footprint infrared technology component that offers high performance, while opening doors for new earth observation measurement capabilities.

    Link

Quantum & 2D Materials

  • J1. Spin Control with a Topological Semimetal, Physics (2020)

    Avik Ghosh


    Topological materials, from graphene to topological insulators, owe their remarkable properties to their two-dimensional surface states, which are protected from disorder and defects by topology and symmetry. A recently discovered class of materials, known as topological semimetals, often exhibit even richer and more robust topological effects. These materials include Dirac semimetals (DSMs) and Weyl semimetals (WSMs) [12], which host electronic excitations behaving like Dirac and Weyl fermions, respectively. One of their intriguing properties is that the spins and momenta of their surface electrons are “locked.” Loosely speaking, this means that right-moving electrons are spin-up polarized, while left-moving ones are spin-down polarized—a behavior that can lead to exotic physics and may be harnessed in spintronic devices. However, it has been challenging to observe spin-polarized currents in these semimetals, mostly because currents are carried by both surface and bulk electrons, and spin-momentum locking isn’t as strong in the latter. Now, a team led by Zhi-Min Liao of Peking University has demonstrated a clever setup that reveals, with simple electrical measurements, spin-polarized transport in a DSM nanowire [3]. The researchers say that the setup can single out the contribution of surface electrons, eliminating that of bulk electrons. What’s more, the configuration allows the spin-polarized signal to be turned on and off with an applied voltage.

    Link
  • J2. Graphene Transistor Based on Tunable Dirac-Fermion-Optics, Proc. Nat. Acad. Sci. USA (2019)

    Ke Wang, Mirza M. Elahi, Lei Wang, K. M. Masum Habib, Takashi Taniguchi, Kenji Watanabe, James Hone, Avik W. Ghosh, Gil-Ho Lee, Philip Kim


    The linear energy-momentum dispersion, coupled with pseudo-spinors, makes graphene an ideal solid-state material platform to realize an electronic device based on Dirac-Fermionic relativistic quantum mechanics. Employing local gate control, several examples of electronic devices based on Dirac fermion dynamics have been demonstrated, including Klein tunneling, negative refraction and specular Andreev reflection. In this work, we present a quantum switch based on analogous Dirac-fermion-optics (DFO), in which the angle dependence of Klein tunneling is explicitly utilized to build tunable collimators and reflectors for the quantum wave function of Dirac fermions. We employ a novel dual-source design with a single flat reflector, which minimizes diffusive edge scattering and suppresses the background incoherent transmission. Our gate-tunable collimator-reflector device design enables measurement of the net DFO contribution in the switching device operation. We measure a full set of transmission coefficients of DFO wavefunction between multiple leads of the device, separating the classical contribution from that of any disorder in the channel. Since the DFO quantum switch demonstrated in this work requires no explicit energy gap, the switching operation is expected to be robust against thermal fluctuations and inhomogeneity length scales comparable to the Fermi wavelength. We find our quantum switch works at an elevated temperature up to 230 K and large bias current density up to 102 A/m, over a wide range of carrier densities. The tunable collimator-reflector coupled with the conjugated source electrodes developed in this work provides an additional component to build more efficient DFO electronic devices.

    Link
  • J3. Atomic scale characterization of graphene p-n junctions for electron-optical applications, ACS Nano (2019)

    Xiaodong Zhou, Alexander Kerelsky, Mirza M. Elahi, Dennis Wang, K. M. Masum Habib, Redwan N. Sajjad, Pratik Agnihotri, Ji Ung Lee, Avik W. Ghosh, Frances M. Ross, and Abhay N. Pasupathy


    Graphene p–n junctions offer a potentially powerful approach toward controlling electron trajectories via collimation and focusing in ballistic solid-state devices. The ability of p–n junctions to control electron trajectories depends crucially on the doping profile and roughness of the junction. Here, we use four-probe scanning tunneling microscopy and spectroscopy (STM/STS) to characterize two state-of-the-art graphene p–n junction geometries at the atomic scale, one with CMOS polySi gates and another with naturally cleaved graphite gates. Using spectroscopic imaging, we characterize the local doping profile across and along the p–n junctions. We find that realistic junctions exhibit non-ideality both in their geometry as well as in the doping profile across the junction. We show that the geometry of the junction can be improved by using the cleaved edge of van der Waals metals such as graphite to define the junction. We quantify the geometric roughness and doping profiles of junctions experimentally and use these parameters in non-equilibrium Green’s function-based simulations of focusing and collimation in these realistic junctions. We find that for realizing Veselago focusing, it is crucial to minimize lateral interface roughness which only natural graphite gates achieve and to reduce junction width, in which both devices under investigation underperform. We also find that carrier collimation is currently limited by the non-linearity of the doping profile across the junction. Our work provides benchmarks of the current graphene p–n junction quality and provides guidance for future improvements.

    Link
  • J4. Impact of geometry and non-idealities on electron 'optics' based graphene p-n junction devices, APL (2019)

    Mirza M. Elahi, K. M. Masum Habib, Ke Wang, Gil-Ho Lee, Philip Kim, and Avik W. Ghosh


    We articulate the challenges and opportunities of unconventional devices using the photon like flow of electrons in graphene, such as Graphene Klein Tunnel (GKT) transistors. The underlying physics is the employment of momentum rather than energy filtering to engineer a gate tunable transport gap in a 2D Dirac cone bandstructure. In the ballistic limit, we get a clean tunable gap that implies subthermal switching voltages below the Boltzmann limit, while maintaining a high saturating current in the output characteristic. In realistic structures, detailed numerical simulations and experiments show that momentum scattering, especially from the edges, bleeds leakage paths into the transport gap and turns it into a pseudogap. We quantify the importance of reducing edge roughness and overall geometry on the low-bias transfer characteristics of GKT transistors and benchmark against experimental data. We find that geometry plays a critical role in determining the performance of electron optics based devices that utilize angular resolution of electrons.

    Link