ABSTRACT: Contacts to transition metal dichalcogenides (TMDs) present several challenges in the context of realizing optimum device performance. In the case of traditional metal contacts, the TMD surface preparation method and the resultant condition plays a prominent role. Recently, the impact of the deposition ambient on contact resistance and the associated metal/TMD interfacial chemistry has been explored. It is found that the control of deposition under conditions where the residual gas pressure is controlled to minimize spurious surface reactions (viz. ultrahigh vacuum (UHV): Pdep ≤ 10-8 mbar) can result in a lower contact resistance for some metal/TMD systems. Comparing in-situ and ex-situ deposition in conjunction with surface/interface analysis of such interfaces reveals substantial differences in the interfacial chemical properties relative to contacts deposited under HV (Pdep ≤ 10-6 mbar) conditions more typical in device fabrication. In addition, the impact of post metal anneals are also presented. The chemical properties can be correlated to the interfacial band alignment and associated barriers with concomitant device measurements.
BIOGRAPHY: Robert M. Wallace received his B.S. in Physics and Applied Mathematics in 1982 at the University of Pittsburgh where he also earned his M.S. (1984) and Ph.D. (1988) in Physics, under Prof. W. J. Choyke. From 1988 to 1990, he was a postdoctoral research associate in the Department of Chemistry at the Pittsburgh Surface Science Center under the late Prof. John T. Yates, Jr.
In 1990, he joined Texas Instruments Central Research Laboratories as a Member of Technical Staff (MTS) in the Materials Characterization Branch of the Materials Science Laboratory and was elected as a Senior MTS in 1996. Dr. Wallace was then appointed in 1997 to manage the Advanced Technology branch in TI’s R&D which focused on advanced device concepts and the associated material integration issues. In 2003, he joined the faculty in the Erik Jonsson School of Engineering and Computer Science at the University of Texas at Dallas (UTD) as a Professor of Electrical Engineering and Physics. He is a founding member of the Materials Science and Engineering program at UTD. Dr. Wallace also has appointments in the Departments of Electrical Engineering, Mechanical Engineering, and Physics.
He has authored or co-authored over 380 publications in peer reviewed journals and proceedings with over 23000 (32000) citations according to Scopus (Google Scholar), and is an inventor on 46 US patents.
He was named Fellow of the AVS in 2007 and an IEEE Fellow in 2009 for his contributions to the field of high-k dielectrics in integrated circuits.
Details can be found at: https://sites.google.com/view/robert-m-wallace