Gas Sensing Characteristics of MoxW1-xS2 Synthesized by Atomic Layer Deposition

Abstract

Two-dimensional Transition metal dichalcogenide (2D TMDC) have been attracted great attention as gas sensing materials with high sensitivity in room temperature. [1] Because of this characteristic, 2D TMDC gas sensor could overcome the oxide-based semiconductor which need heating for gas sensing. Therefore, various 2D TMDC gas sensor studies have been ongoing. Recently, it has been shown that the gas sensor property could be improved through the changing the composition in WS2xSe2-2x alloy. [2] Here we report a synthesis method of MoxW1-xS2 alloys for gas sensor by atomic layer deposition. Layer controlled 2D MoS2 and WS2 were synthesized with Mo(CO)6, W(CO) 6 and H2S as precursors and reactant. For the first time, we systematically modulate the composition of MoxW1-xS2 alloys by changing the configuration of low-temperature ALD super-cycles. AFM and Raman spectroscopy results of MoxW1-xS2 alloys demonstrate that the thickness of alloy is accurately controlled by ALD. Also XPS results confirmed that composition of alloy is precisely controlled by ALD super-cycles. Furthermore, gas sensors fabricated by MoxW1-xS2 alloys were evaluated for NO2 gas. It showed response time and recovery characteristics of MoxW1-xS2 alloy gas sensor is dramatically enhanced.