Prospects for High Carrier Mobility in the Cubic Germanates

Barium stannate (BaSnO₃) has attracted considerable interest on account of its wide band gap and record-high room-temperature mobility (320 cm²V^-1s^-1); however, comparatively little attention has been paid to the cubic germanates (SrGeO₃ and BaGeO₃). Here, we comprehensively examine the electronic structure properties of both materials using density functional theory calculations with an accurate hybrid functional. We find that the germanates have wide band gaps and low carrier effective masses; the hole effective masses, in particular, are considerable smaller than those of BaSnO₃ [1]. We then proceed to consider electron mobility in SrGeO₃, the most promising system based on reports of its experimental synthesis. We find SrGeO₃ to have a total electron mobility between 400 and 500 cm²V^-1s^-1, significantly surpassing our previously calculated value for BaSnO₃, value and making it worthy of further study.

[1] A.J.E. Rowberg, K. Krishnaswamy, C.G. Van de Walle, Semicond. Sci. Tech. 35, 085030 (2020).