Intrinsic defects in gallium sulfide monolayer: a first-principles study

Abstract

The electronic and magnetic properties of native point defects, including vacancies (V_Ga and V_S), antisites (Ga_S and S_Ga) and interstitials (Ga_i and S_i) in monolayer and bulk GaS, were systemically studied using the density functional theory method. For the monolayer, the impurity states appeared in the band gaps of all defect structures except interstitial S_i. Half-metallic behavior can be obtained in the presence of V_Ga and Ga_i. Monolayers with V_Ga, Ga_S, S_Ga and Ga_i had a total magnetic moment of 1.0 μ_B, as did the bulk samples with V_Ga, Ga_S and S_Ga, whereas the monolayers with V_S and S_i and bulk sample with Ga_i were spin-unpolarized. In addition, n- and p-type GaS monolayers were obtained under Ga-rich and S-rich conditions, respectively. Ga_S and S_Ga were identified as suitable n- and p-type defects, respectively.