Ge3P2: New viable two-dimensional semiconductors with ultrahigh carrier mobility

Abstract

The two-dimensional germanium phosphide (GeP) and germanium arsenide (GeAs and GeAs2) were recently realized (Adv. Mater. 2018, 30, 1706771; Adv. Funct. Mater. 2018, 28, 1707379; Adv. Mater. 2018, 30, 1705934; Adv. Mater. 2018, 1804541) to extend the fast growing 2D materials family. In this work, other possible 2D GexPy structures are systematically investigated through the combination of the stochastic search strategy (RG2) and density functional theory. The RG2 code repeats all the previously proposed GexPy layers and provides two new Ge3P2 structures (Cmmm-Ge3P2 and P4/mbm-Ge3P2). The calculated formation enthalpy shows that Cmmm-Ge3P2 and P4/mbm-Ge3P2 are two new viable phases locating at the convex hull. They are further confirmed to be dynamically and mechanically stable semiconductors with indirect band gaps of 1.62 eV and 1.89 eV, respectively, and their electronic properties can be effectively modulated by uniaxial strains. The evaluated electron mobilities of Cmmm-Ge3P2 and P4/mbm-Ge3P2 are 1.05 × 105 cm2 V−1 s−1 and 6.29 × 104 cm2 V−1 s−1, respectively, which are comparable to the mobility of graphene. These desirable properties of Cmmm-Ge3P2 and P4/mbm-Ge3P2 provide promising opportunities for diverse applications in electronic and optoelectronic nanodevices.