Prof.  Dipl. Ing.  Islam Aynul
University of Glasgow,  UK

Title: Monte Carlo Simulation of Strained-Channel Architectures for 22 nm Gate-Length NMOS: A Comparative Study of Relaxed SiGe, Strained Si, and Strained SiGe

Abstract:

The continued scaling of CMOS technology has driven strong interest in strain engineering to enhance carrier transport in nanoscale devices. In this work, we present a comparative study of three n-MOSFET channel architectures at a 22 nm gate length using self-consistent ensemble Monte Carlo device simulation with a five-valley (Γ, L, X) conduction-band model. The architectures examined are a relaxed Si1−xGex channel as a baseline, a tensile-strained Si channel on a relaxed SiGe virtual substrate in which biaxial tension lowers the ∆2 valleys and suppresses intervalley scattering, and a compressively-strained SiGe channel on a Si substrate in which biaxial compression lowers the in-plane ∆4 valleys. Strain-induced valley splitting is computed from deformation-potential theory and incorporated into the band structure, scattering rates, and effective masses of each material. The simulations resolve electron velocity, sheet carrier density, and drain current under matched bias conditions, isolating the transport advantage of each strain configuration. The strained-Si-on-SiGe architecture provides the largest electron transport enhancement, owing to the absence of alloy scattering and favourable ∆2 valley occupancy, consistent with reported experimental mobility enhancements of ∼75% and transconductance gains of ∼60% for strained-Si NMOS, while the strained-SiGe channel offers a competitive alternative through compressive-strain valley engineering. In agreement with prior full-band studies, the enhancement at this gate length is found to arise predominantly from reduced scattering and valley repopulation rather than from a change in saturation velocity. The study highlights the dominant role of strain over alloy composition in determining transport at the deca-nanometre scale and provides design guidance for strain-engineered Si/SiGe NMOS devices.

Biography:

Aynul Islam award his PhD degree in Electronics and Electrical engineering from the University of Glasgow/Swansea University, United Kingdom. He has done research and development on the area of Monte Carlo Device Modelling of Electron Transport in nanoscale transistors. He finished his master’s degree (Diplom Ingenieur, DI) in Technical Physics from the Johannes Kepler University, Austria. He has done his research on Erbium in Silicon Influence of Hydrogenation and Waveguiding. He has been continuing his research with analytical and numerical simulation using finite element, code developing, random matrix theory, quantum-mechanical treatments based on Schrödinger equation. His research interests on the area of Nanotechnology, Modelling and Simulation (Monte Carlo), Nanomaterials, Solar Cell, Photovoltaic, Photoluminescence Measurements, Heterostructure Devices using Lithography, Photonic Crystal. At present, he has been working as an Associate Professor in University of Electronic Science and Technology of China (UESTC), China, Glasgow College, Collaborated with University of Glasgow, United Kingdom. During his teaching and research, he achieved the status of Fellow in Higher Education Academy, Bangor University, UK. He recently awarded Teacher of the year 2020 Student Led Teaching Awards, Bangor University, and Teacher of the year 2024 at the Glasgow College, University of Glasgow, UK. He got strong publication in high quality journal with strong impact factor and published two books on nanotechnology and quantum mechanics.