Ternary Wide Band Gap Oxides for High-Power Electronics Identified Computationally

TL;DR

This study computationally identifies new wide band gap oxides with superior thermal and electrical properties for high-power electronics, expanding the pool of potential materials beyond current options.

Contribution

It introduces a large-scale computational screening of 1,340 metal-oxides to find promising WBG semiconductors with high thermal conductivity and power efficiency, highlighting several novel candidates.

Findings

40 oxides with higher thermal conductivity than $eta$-Ga$_2$O$_3$

Candidates surpassing SiC and GaN in BFOM

Identification of promising materials like In$_2$Ge$_2$O$_7$, Mg$_2$GeO$_4$, and InBO$_3$

Abstract

As electricity grids become more renewable energy-compliant, there will be a need for novel semiconductors that can withstand high power, high voltage, and high temperatures. Wide band gap (WBG) semiconductors tend to exhibit large breakdown field, allowing high operating voltages. Currently explored WBG materials for power electronics are costly (GaN), difficult to synthesize as high-quality single crystals (SiC) and at scale (diamond, BN), have low thermal conductivity ($\beta$-Ga$_2$O$_3$), or cannot be suitably doped (AlN). We conduct a computational search for novel semiconductors across 1,340 known metal-oxides using first-principles calculations and existing transport models. We calculate the Baliga figure of merit (BFOM) and lattice thermal conductivity ($\kappa_L$) to identify top candidates for n-type power electronics. We find 40 mostly ternary oxides that have higher $\kappa_L$ than $\beta$-Ga$_2$O$_3$ and higher n-type BFOM than SiC and GaN. Among these, several material classes emerge, including 2-2-7 stoichiometry thortveitites and pyrochlores, II-IV spinels, and calcite-type borates. Within these classes, we propose In$_2$Ge$_2$O$_7$, Mg$_2$GeO$_4$, and InBO$_3$ as they are the most favorable for n-type doping based on our preliminary evaluation and could be grown as single crystals or thin film heterostructures. These materials could help advance power electronic devices for the future grid.