Rutile germanium dioxide: An emerging ultrawide bandgap semiconductor for power device applications – A review

Abstract

In recent years, the demand for wide and ultrawide bandgap (UWBG) semiconductors for advanced power electronics and optoelectronic devices has surged. Materials in this class, including GaN, AlN, AlGaN, diamond, c-BN, Ga₂O₃, and emerging candidates like rutile GeO₂, are of particular interest due to their potential for high-efficiency, high-power applications. Rutile GeO₂, with a bandgap around 4.7 eV, possesses excellent electrical, optical, mechanical, and thermal properties, making it a strong contender among UWBG semiconductors. This review examines rutile GeO₂’s structural, electronic, and optical characteristics, focusing on films deposited using methods such as MOCVD, MBE, CVD, and sputtering. The rutile phase of GeO₂ demonstrates notable versatility, as it can be doped for both n- and p-type conduction with elements like Al, In, and As. Recent advancements have enabled the growth of high-quality, epitaxial rutile GeO₂ films, broadening its potential applications. Additionally, large-scale rutile GeO₂ can be produced through melt and flux methods, an advantage for commercial scalability. These qualities highlight rutile GeO₂’s promise as a next-generation material for power devices and optoelectronics, meriting increased research and investment to fully leverage its capabilities.