Materials Science and Engineering Location: Zoom (e-mail presenter for link)
Add to Calendar 2022-02-01T14:00:00 2022-02-01T14:00:00 America/New_York Doctoral Dissertation Proposal- Samantha Jaszewski Effects of Deposition and Processing Parameters on Phase Constitution, Microstructure, and Ferroelectric Properties of Hafnium Oxide Thin Films   Committee:          Dr. Stephen McDonnell (Chair) Dr. Petra Reinke Dr. Arthur Lichtenberger Dr. Steve Consiglio Dr. Jon Ihlefeld (Advisor)                                  Abstract: Zoom (e-mail presenter for link)

Effects of Deposition and Processing Parameters on Phase Constitution, Microstructure, and Ferroelectric Properties of Hafnium Oxide Thin Films

 

Committee:         

Dr. Stephen McDonnell (Chair)

Dr. Petra Reinke

Dr. Arthur Lichtenberger

Dr. Steve Consiglio

Dr. Jon Ihlefeld (Advisor)                               

 

Abstract:

Since the first report of ferroelectricity in hafnium oxide (HfO2) doped with SiO2 in 2011, significant research efforts have been directed toward understanding the switchable spontaneous polarization in this material. HfO2 is chemically compatible with silicon, is currently used as a high-κ dielectric in CMOS devices, and in the ferroelectric phase is not susceptible to the thickness scaling effects that impose application limitations on traditional ferroelectrics. Thus, this material presents opportunities for technological developments in devices, such as renewed scaling of ferroelectric random access memory (FeRAM), renewed development of ferroelectric field effect transistors (FeFETS), and new devices such as ferroelectric tunnel junctions (FTJs) that previously required epitaxial growth.

The wide-scale adoption of ferroelectric HfO2 into devices is constrained, in part, by an inability to prepare phase-pure films. In equilibrium at room temperature and atmospheric pressure, HfO2 exists in the nonpolar monoclinic phase. Multiple metastable phases exist, including an orthorhombic phase and a tetragonal phase, which can be stabilized by various factors. Ferroelectricity in HfO2 has been attributed to the non-centrosymmetric Pca21 orthorhombic phase. Several factors have been shown to impact phase constitution including dopant type and concentration, biaxial stress, oxygen vacancies, and film thickness or grain size.

This proposed work will evaluate the use of deposition and processing parameters to tailor film properties such as oxygen content, nucleation behavior, and microstructure, which will enable preparation of phase-pure ferroelectric HfO2-based thin films. Phase-pure films will allow us to overcome the challenges associated with this material including an unstable polarization response with electric field cycling and scalability.

Please e-mail Ms. Jaszewski for the Zoom link stj6ze@virginia.edu 

All interested persons are invited to attend.