Strain can efficiently modulate the bandgap and carrier mobilities in two-dimensional (2D) materials. Conventional mechanical strain-application methodologies that rely on flexible, patterned or nano-indented substrates are severely limited by low thermal tolerance, lack of tunability and/or poor scalability. Here, we leverage the converse piezoelectric effect to electrically generate and control strain transfer from a piezoelectric thin film to electro-mechanically coupled ultra-thin 2D MoS2. Electrical bias polarity change across the piezoelectric film tunes the nature of strain transferred to MoS2 from compressive ∼0.23% to tensile ∼0.14% as verified through peak shifts in Raman and photoluminescence spectroscopies and substantiated by density functional theory calculations. The device architecture, built on a silicon substrate, uniquely integrates an MoS2 field-effect transistor on top of a metal-piezoelectric-metal stack enabling strain modulation of transistor drain current 130×, on/off current ratio 150×, and mobility 1.19× with high precision, reversibility and resolution. Large, tunable tensile (1056) and compressive (-1498) strain gauge factors, easy electrical strain modulation, high thermal tolerance and substrate compatibility make this technique promising for integration with silicon-based CMOS and micro-electro-mechanical systems.
@article{arxiv.2304.13154,
title = {Electrically Controlled Reversible Strain Modulation in MoS$_2$ Field-effect Transistors via an Electro-mechanically Coupled Piezoelectric Thin Film},
author = {Abin Varghese and Adityanarayan Pandey and Pooja Sharma and Yuefeng Yin and Nikhil Medhekar and Saurabh Lodha},
journal= {arXiv preprint arXiv:2304.13154},
year = {2023}
}