1 p.m. - 2 p.m. Location: ECSS 3.503
From the perspective of a physicist, Si CMOS technology has been operating on the same basic “semi-classical” physics principles established in the 1940's. In the 1980’s the introduction of explicitly quantum mechanical effects into III-V transistors proved transformative in terms of high frequency and low noise performance. However, nothing similar happened in Si CMOS because of significant challenges in fabricating quantum device structures in a manner amenable to industrial fabrication. In this seminar I will describe our efforts to integrate a quantum well (QW) into the inversion channel of Si NMOS transistors fabricated on an industrial 45 nm process line. These transistors use lateral ion implantation to define a QW whose potential depth is controlled by the gate voltage. In these devices we have observed explicit quantum transport signatures in the form of negative differential transconductance (NDT) up to room temperature. The NDT signature results from the gate voltage bringing the QW’s discrete quantized state energies first into and then out of alignment with the drain-source energy. I will present the basic QW CMOS device performance characteristics such as NDT strength, gain, and temperature dependence, and also describe some circuit applications, such as a folding frequency multiplier, that take advantage of the quantum transfer function. Finally, I will discuss the results of quantum device simulations that point out a route towards improved designs for a QW device.
Dr. Mark Lee is Professor of Physics and Materials Science and Physics Department Head at the University of Texas at Dallas (UTD). He is also an affiliated faculty member in the Department of Materials Science & Engineering and in the Texas Analog Center of Excellence (TxACE) at UTD. Prof. Lee received his Ph.D. in Applied Physics from Stanford University in 1991 with a thesis in the field of superconductivity. After a two-year postdoc at the NEC Research Institute in Princeton, NJ where he worked on semiconductor superlattices, he joined the physics faculty at the University of Virginia where he led research into highly correlated electron glasses and terahertz properties of superconductors. In 1999, he joined Bell Laboratories–Lucent Technologies in Murray Hill, NJ as a Member of Technical Staff, where he worked until 2003. Prior to taking up his present position at UTD in September 2010, Prof. Lee was a Principal Member of Technical Staff and Manager of the Center for Integrated Technologies Science Department at Sandia National Laboratories in Albuquerque, NM.
Prof. Lee’s research focuses on electrodynamic and quantum mechanical properties of novel materials, nanomaterials, and electronic and photonic devices. In this context, “electrodynamic” means interactions of a material or device with time-dependent electromagnetic fields ranging in frequency from 10 GHz to ~100 THz. This frequency spectrum spans the range of interest to both current and future telecommunications and computation technologies and to fundamental many-particle quantum correlation energies in solid-state systems. “Quantum mechanical” refers to measuring explicitly quantum phenomena, such as charge or conductance quantization or the existence of forbidden energy gaps. He has done extensive work on high-frequency electrical conductivity in ultra-high mobility 2-dimensional electron gases, non-linear electromagnetic frequency mixing in superconductors, dispersion and loss properties of optically non-linear and high-dielectric constant dielectrics, and quantum and electrodynamic properties of interacting electron glasses. For accomplishments in physics research, Prof. Lee was named a Fellow of the American Physical Society (APS) in 2005 and Chair of the APS Forum on Industrial & Applied Physics in 2008.
Donna Kuchinski, 972-883-5556
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