Dhara Sushovan, Jawa Himani, Ghosh Sayantan, Varghese Abin, Karmakar Debjani, Lodha Saurabh
Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India.
Department of Materials Science and Engineering, Monash University, Clayton, Victoria 3800, Australia.
ACS Appl Mater Interfaces. 2021 Jul 7;13(26):30785-30796. doi: 10.1021/acsami.1c01806. Epub 2021 Jun 28.
Two-dimensional MoS gas sensors have conventionally relied on a change in field-effect-transistor (FET) channel resistance or in the Schottky contact/pn homojunction barrier. We demonstrate an enhancement in sensitivity (6×) and dynamic response along with a reduction in detection limit (8×) and power (10×) in a gate-tunable type-II WSe(p)/MoS(n) heterodiode gas sensor over an MoS FET on the same flake. Measurements for varying NO concentration, gate bias, and MoS flake thickness, reinforced with first-principles calculations, indicate dual-mode operation due to (i) a series resistance-based exponential change in the high-bias thermionic current (high sensitivity), and (ii) a heterointerface carrier concentration-based linear change in near-zero-bias interlayer recombination current (low power) resulting in sub-100 μW/cm power consumption. Fast and gate-bias tunable recovery enables an all-electrical, room-temperature dynamic operation. Coupled with the sensing of trinitrotoluene (TNT) molecules down to 80 ppb, this study highlights the potential of the WSe/MoS pn heterojunction as a simple, low-overhead, and versatile chemical-sensing platform.
二维硫化钼气体传感器传统上依赖于场效应晶体管（FET）沟道电阻或肖特基接触/pn同质结势垒的变化。我们展示了一种栅极可调谐的II型硒化钨（p）/硫化钼（n）异质结气体传感器，与同一薄片上的硫化钼场效应晶体管相比，其灵敏度提高了6倍，动态响应增强，同时检测限降低了8倍，功耗降低了10倍。对不同的一氧化氮浓度、栅极偏置和硫化钼薄片厚度进行测量，并辅以第一性原理计算，结果表明该传感器具有双模式工作特性，这是由于：（i）高偏置热电子电流中基于串联电阻的指数变化（高灵敏度），以及（ii）近零偏置层间复合电流中基于异质界面载流子浓度的线性变化（低功耗），从而实现了低于100μW/cm²的功耗。快速且栅极偏置可调的恢复特性实现了全电学、室温动态操作。结合对低至80 ppb的三硝基甲苯（TNT）分子的传感，本研究突出了硒化钨/硫化钼pn异质结作为一种简单、低开销且通用的化学传感平台的潜力。
