Electronic and magnetic properties of SnSe monolayers doped by Ga, In, As, and Sb: a first-principles study.

A SnSe monolayer with an orthorhombic Pnma GeS structure is an important two-dimensional (2D) indirect band gap material at room temperature. Based on first-principles density functional theory calculations, we present systematic studies on the electronic and magnetic properties of X (X = Ga, In, As, Sb) atom doped SnSe monolayers. The calculated electronic structures show that the Ga-doped system maintains its semiconducting properties while the In-doped SnSe monolayer is half-metal. The As- and Sb-doped SnSe systems present the characteristics of an n-type semiconductor. Moreover, all considered substitutional doping cases induce magnetic ground states with a magnetic moment of ∼ 1 μB. In addition, the calculated formation energies also show that four types of doped systems are thermodynamically stable. These results provide a new route for the potential applications of doped SnSe monolayers in 2D photoelectronic and magnetic semiconductor devices.