Stability, growth, and doping of In2(Si, Ge)2O7: Promising <i>n</i>-type wide-bandgap semiconductors

In this paper, we investigate, computationally and experimentally, the phase stability, electronic structure properties, and the propensity for n-type doping of In2X2O7 (X = Si, Ge) ternary oxides. This family of materials contains promising novel wide-gap semiconductors based on their estimated high n-type Baliga figures of merit and acceptable thermal conductivity for power electronics applications. Here, we predict that both In2Si2O7 and In2Ge2O7 are n-type dopable, with Zr providing between 1016 and above 1021 cm−3 net donor concentrations under O-poor conditions, depending on the chemistry, structure (ground-state thortveitite or high-pressure pyrochlore), and synthesis temperature. To verify our predictions, we synthesize Zr-doped In2Ge2O7 in the thortveitite structure and measure its electrical properties. Initial thin-film growth and annealing lead to polycrystalline thin films with bandgaps over 4 eV and confirm Zr doping predictions by achieving electron concentrations at 1014–1016 cm−3 even under O-rich conditions. While future epitaxial growth development is still needed, this study establishes In2X2O7 as promising n-type wide-gap semiconductors for power electronic applications.