B.S. ​Applied Physics 1st class honors; Dublin City University, 2004Ph.D. ​Physical Sciences; Dublin City University, 2009

"Our group advances the science of 2-D materials, a field that will enable the next generation of advances in electronic and medical devices."

Stephen J. McDonnell, Assistant Professor

Stephen McDonnell’s current research focuses on understanding how 2D materials, such as the transition metal dichalcogenide family, interface with other materials in electronic devices. Interfaces play a critical role in the performance of electronic devices. As such, understanding the bonding in heterostructures is crucial to enabling the interface engineering required to integrate materials into nanoelectronic device architectures. In our lab, we have established a dedicated growth and characterization ultra-high vacuum system that allows us to, not only synthesize high purity 2D semiconductors, but also to investigate the structure, composition, and electronic properties of these materials prior to any atmospheric exposure. Without breaking vacuum we also deposit device relevant insulators and metals to enable a detailed understanding of how such structures impact the electronic properties of the semiconductor. In addition to our nanoelectronic focused work, we continue to explore the wider applications of transition metal dichalcogenides in optoelectronics and photocatalysis.

Research Interests

  • Electronic Material Integration
  • Nanoelectronics and 2-D Materials
  • Surface and Interface Science and Engineering
  • Energy Conconversion
  • Nanomaterials and nanomanufacturing

Selected Publications

  • In-Vacuo Studies of Transition Metal Dichalcogenide Synthesis and Layered Material Integration ABS K. M. Freedy, P. M. Litwin, S. McDonnell
  • Atomically-thin layered films for device applications based upon 2D TMDC materials ABS S. McDonnell, R.M. Wallace
  • MoS2–titanium contact interface reactions ABS S McDonnell, C Smyth, CL Hinkle, RM Wallace
  • GaSb Oxide Thermal Stability studied by Dynamic-XPS. Journal of Vacuum Science and Technology B, 32, (2014), 041201 ABS S. McDonnell, B. Brennan, K. Winkler, P. Baumann, E. Bursa and R. M. Wallace
  • Hole Contacts on Transition Metal Dichalcogenides: Interface Chemistry and Band Alignments. ACS Nano, 8 (6), (2014) 6265–6272 ABS S. McDonnell, A. Azcatl, R. Addou, C. Gong, C. Battaglia, S. Chuang, K. Cho, A. Javey and R. M. Wallace
  • MoS2 Functionalization for Ultra-thin Atomic Layer Deposited Dielectrics. Applied Physics Letters, 104, (2014), 111601 ABS A. Azcatl, S. McDonnell, S. KC, X. Peng, H. Dong, X. Qin, R. Addou, G. I. Mordi, N. Lu, J. Kim, M. Kim, K. Cho, and R. Wallace
  • Defect Dominated Doping and Contact resistance in MoS2. ACS Nano 8 (3), (2014) 2880-2888 ABS S. McDonnell, R. Addou, C. Buie, R. M. Wallace, C. L. Hinkle
  • HfO2 on MoS2 by Atomic Layer Deposition: Adsorption Mechanisms and Thickness Scalability. ACS Nano 7 (11), (2013) 10354–10361 ABS S. McDonnell, B. Brennan, A. Azcatl, N. Lu, H. Dong, C. Buie, J. Kim, C. L. Hinkle, M. J. Kim and R. M. Wallace
  • Controlling the Atomic layer Deposition of Titanium Dioxide on Silicon: Dependence on Substrate Termination. The Journal of Physical Chemistry C 117, (2013) 20250-20259 ABS S. McDonnell, R. C. Longo, O. Seitz, J. B. Ballard, G. Mordi, D. Dick, J. H. G. Owen, J. N. Randall, J. Kim, Y. J. Chabal, K. J. Cho, R. M. Wallace
  • Interfacial oxide re-growth in thin film metal oxide III-V semiconductor systems. Applied Physics Letters 100 (2012) 141606 ABS S. McDonnell, H. Dong, J. M. Hawkins, B. Brennan, M. Milojevic, F. S. Aguirre-Tostado, D. M. Zhernokletov, C. L. Hinkle, J. Kim, R. M. Wallace
  • In situ X-ray photoelectron spectroscopy characterization of GaSb interface evolution. Applied Surface Science 257(20) (2011) 8747-8751 ABS S. McDonnell, D. M. Zhernokletov, A. P. Kirk, R. M. Wallace
  • The effect of graphite surface condition on the composition of Al2O3 by atomic layer deposition. Applied Physics Letters 97 (2010) 082901 ABS A. Pirkle, S. McDonnell, B. Lee, J. Kim, L. Columbo, R. M. Wallace