CBE Colloquia - Low-Power 2D CMOS and Optoelectronic Devices via Oxidation Treatment of Tungsten Diselenide
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Two-dimensional (2D) transition metal dichalcogenides (TMDs) such as tungsten diselenide (WSe₂) have potential for next-generation CMOS and optoelectronic devices due to their atomically thin structure and tunable electrical properties. Key challenges in 2D TMD CMOS include achieving high-performance p-type field effect transistors (FETs), as well as seamless integration of balanced n- and p-type devices for scalable logic circuits. Surface oxidation induces p-type doping in WSe₂ through a self-limiting tungsten oxide (WOₓ) layer, enabling efficient hole injection in WSe₂ p-FETs via surface charge transfer. By selectively removing WOₓ, we fabricate close-proximity n- and p-FETs on a single WSe₂ flake, achieving low power inverter operation. Photodiode measurements demonstrate stable on-off switching under low-power laser excitation with fast response times, low dark current, gate-controllable responsivity, and self-powered operation at zero bias. Such surface treatment enables single-material pn junctions, potentially simplifying material synthesis and streamlining fabrication, attractive for scalable 2D CMOS technologies.
Luke Smith serves as Assistant Professor in Physics at National Cheng Kung University, having joined the faculty in 2022. Luke received his bachelors and master’s degree in Electrical and Electronic Engineering from the University of Oxford, U.K., and PhD in Physics from the University of Cambridge, U.K. His expertise range from quantum transport and device physics, nanoscale fabrication, two-dimensional materials, quantum computing, and the scalability of quantum devices using multiplexing schemes. His current research focuses on the electronic characteristics of two-dimensional semiconductors, enhancing performance of TMD-based transistors and exploring their fundamental properties.