Abstract
Transition metal dichalcogenides (TMDs) are an important class of materials for future microelectronics. Of particular interest are TMDs deposited by atomic layer deposition (ALD) since this technique allows both back-end-of-line (BEOL) compatible deposition and the ability to create heavily-doped regions for contact formation. In this presentation, I will describe progress on the growth and integration of heavily-doped TMDs to create contacts for 2D-channel MOSFETs. I will first describe the results of transport measurements on Nb-doped WS2 (Nb:WS2) thin films grown by plasma-enhanced ALD (PE-ALD). We first studied the Nb:WS2 thin film properties using transfer length measurements and determined the contact resistance, carrier mobility, and carrier concentration as a function of Nb atomic fraction and contact metal. Contact resistance values as low as 300 Ω–μm were achieved, with specific contact resistivity as low as 11 nΩ-cm2. We also characterized the transport properties of Nb:WS2 thin films deposited on CVD-grown WSe2 and found increased mobility indicative of charge transfer from the Nb:WS2 into the WSe2, in agreement with DFT calculations. Short-channel WSe2 p-MOSFETs using Nb:WS2 contacts were fabricated and characterized, and these devices showed promising on-state current with low contact resistance. Finally, I will provide an outlook for future research needed to address some of the outstanding issues that need to be overcome to enable the implementation of ALD-deposited TMDs into next-generation advanced-node CMOS devices.
Bio
Dr. Koester is the Frank M. Freimann Professor of Microelectronics, and Director of Notre Dame Nanoscience and Technology (NDnano) at the University of Notre Dame. He received B.S.E.E. and M.S.E.E. degrees from Notre Dame in 1989 and 1991, and the Ph.D. in 1995 from the University of California, Santa Barbara. From 1997 to 2010, he was a research staff member at the IBM T. J. Watson Research Center and performed research on a wide variety of electronic and optoelectronic devices, with an emphasis on those using the Si/SiGe material system. From 2006 to 2010 he served as manager of Exploratory Technology at IBM Research where his team investigated advanced devices and integration concepts for use in future generations of microprocessor technology. From 2010-2025, Dr. Koester was a Professor of Electrical & Computer Engineering at the University of Minnesota, where his research focused on novel electronic, photonic, spintronic, and sensing device concepts. Dr. Koester has authored or co-authored over 300 technical publications and conference presentations, 7 volumes, 4 book chapters, and holds 82 United States patents. He is a Fellow of the IEEE, Optica, and the National Academy of Inventors.
