Electrically Controlled High Sensitivity Strain Modulation in MoS<sub>2</sub> Field-Effect Transistors via a Piezoelectric Thin Film on Silicon Substrates.

Varghese, Abin; Pandey, Adityanarayan H; Sharma, Pooja; Yin, Yuefeng; Medhekar, Nikhil V; Lodha, Saurabh · Nano Lett · 2024

basic_science · Level V

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Abstract

Strain can modulate bandgap and carrier mobilities in two-dimensional (2D) materials. Conventional strain-application methodologies relying on flexible/patterned/nanoindented substrates are limited by low thermal tolerance, poor tunability, and/or scalability. Here, we leverage the converse piezoelectric effect to electrically generate and control strain transfer from a piezoelectric thin film to electromechanically coupled 2D MoS<sub>2</sub>. Electrical bias polarity change across the piezo film tunes the nature of strain transferred to MoS<sub>2</sub> from compressive (∼0.23%) to tensile (∼0.14%) as verified through Raman and photoluminescence spectroscopies and substantiated by density functional theory calculations. The device architecture, on silicon substrate, integrates an MoS<sub>2</sub> field-effect transistor on a metal-piezoelectric-metal stack enabling strain modulation of transistor drain current (130×), on/off ratio (150×), and mobility (1.19×) with high precision, reversibility, and resolution. Large, tunable tensile (1056) and compressive (-1498) strain gauge factors, electrical strain modulation, and high thermal tolerance promise facile integration with silicon-based CMOS and micro-electromechanical systems.