Sheet doping for improved sensitivity of HCl on MoTe2

MoTe2 sheets have shown high sensitivity towards important gas molecules, such as NO2 and NH3. This, in combination with the improved surface recovery via gate bias and UV light, makes MoTe2 a promising platform for high-performance gas detection. However, similar to MoS2, the sensitivity of MoTe2 to other compounds is low making the number of compatible analytes limited. Recent reports have demonstrated that CVT and CVD methods can produce large-size highly-doped sheets of MoTe2 , which opens a new avenue of sheet engineering for enhanced molecular sensing. This work investigates, employing DFT calculations, doping of MoTe2 with Ga, Ge, As, Se, and Br for enhanced HCl detection. The results show that the effects on adsorption are correlated with the partial charge accumulated on the doped element. As and Se are predicted to increase the hole transfer into the sheet by 65 and 20%, respectively, with a limited impact on the adsorption energy of the molecule. The latter is shown, via ab-initio molecular dynamics, to have effectively no impact on the HCl diffusion at room temperature. Hence, As and Se doping is predicted to enhance the response of the sheet to changes in concentration of HCl without impeding its surface recovery.