First-principles investigation on the interface of transition metal dichalcogenide MX2 (M = Mo, W; X = S, Se) monolayer on Al2O3(0001)

By performing first-principles calculation, we studied the interface of transition metal dichalcogenides MX2 (M = Mo, W; X = S, Se) monolayer on Al2O3(0001) substrate for applications in field effect transistor. We firstly examined the 1H, 1T and ZT phases of MX2 monolayers and found that the 1H structure is the best channel material among the three polytypes of MX2. 1H MX2 on both the Al and O terminated Al2O3(0001) substrate are energetically favorable. Systems of MX2 on Al-terminated Al2O3(0001) substrate have larger band gaps than the counterpart of O-terminated Al2O3(0001) substrate. More importantly, WS2 on Al-terminated Al2O3(0001) substrate is the most stable one and has a direct band gap of 1.79 eV. Furthermore, we investigated the effect of intrinsic defects on the electronic properties of WS2/Al2O3(0001) interface. Our calculation results show that Al, W, S vacancy exhibit p-type doping and n-type doping is obtained for O vacancy, and all of these vacancy defects induce defect states in the band gap for both the Al terminated and O terminated WS2/Al2O3 systems. (C) 2016 Elsevier B.V. All rights reserved.