Synthesis and characterization of 1T′ and 2H phase coexistence 2D Re1-xMoxS2 alloy films and their application for photodetectors

Abstract

Alloying is considered an efficient strategy to engineer the crystal structure, modulate the energy band structure and charge carrier concentration by adjusting the elemental composition of transition metal dichalcogenides (TMDs). Here, the two-dimensional (2D) Re1-xMoxS2 alloy films with tunable composition and phase structure were prepared on mica substrates by chemical vapor deposition (CVD) method. The back-gated field effect transistors (FETs) based on 2D Re1-xMoxS2 alloy films were prepared. The Mo component x in 2D Re1-xMoxS2 alloy films was varied from 0, 0.2, 0.4, 0.5, 0.6, 0.8–1 by changing mole ratio of ReO3 to MoO3 while the total number of moles remains the same. The Mo composition-dependent morphology phase structure, electrical transport properties and photoelectric properties of Re1-xMoxS2 alloy films were studied in detail. The results indicate that the 1T′ phase Mo-doped ReS2 and 2H phase Re-doped MoS2 coexist, and the ratio of 2H phase Re-doped MoS2 to 1T′ phase Mo-doped ReS2 can be modulated by changing Mo component x in Re1-xMoxS2 alloy films. 1T′ phase Mo-doped ReS2 exhibits the p-type conduction feature while 2H phase Re-doped MoS2 shows the n-type conduction behavior. The Re1–xMoxS2 alloy devices show obvious photoelectric response to 405, 532, 635 and 808 nm lasers irradiation. The Re0.5Mo0.5S2 (x= 0.5) has the maximum responsivity R of 1024.1 mA/W and external quantum efficiency EQE of 239.3% under 532 nm laser irradiation.