In situ strain electrical atomic force microscopy study on two‐dimensional ternary transition metal dichalcogenides

Abstract Atomically thin two‐dimensional (2D) alloys have attracted wide interests of study recently due to their potential in flexible electronic and optoelectronic applications. In particular, monolayer transition metal dichalcogenide (TMD) alloys have emerged as unique 2D semiconductors with tunable bandgaps, by means of alloying. However, response of surface electrical potential and barrier height to strain for 2D TMD alloys–electrode interface is rarely explored. Apparently, revealing such strain‐dependent evolution of electrical properties is crucial for developing advanced 2D TMD based flexible electronics and optoelectronics. Here we performed in situ strain Kelvin probe force microscopy (KPFM) and conductive atomic force microscopy (C‐AFM) investigations of monolayer Mo 0.4 W 0.6 Se 2 on Au coated flexible substrate, where controlled uniaxial tensile strain is applied. Both contact potential difference (CPD) and Schottky barrier heights (SBH) of monolayer Mo 0.4 W 0.6 Se 2 show obvious decreases with the increase of strain, which is mainly due to the strain‐induced increment of TMD electron affinity. Our in situ strain photoluminescence (PL) measurements also indicate the changes of electronic band structures under strain. We further exploit the substrate effects on CPD by study the monolayer alloy on the mostly used substrates of SiO 2 /Si and indium tin oxide (ITO)/glass. Our findings could strengthen the foundation for the potential applications of 2D TMD and their alloys in the fields of strain sensors, flexible photodetectors, and other wearable electronic devices. image