Defect-Controlled p-Type Conductivity in an Ultrawide-Bandgap ZnGa2O4 Film

Abstract

Ultrawide-bandgap (UWBG) semiconductors are central to next-generation power electronics and deep-UV optoelectronics, yet the absence of reliable p-type materials remains a critical bottleneck. Here, we demonstrate stable intrinsic p-type conductivity in the spinel UWBG oxide ZnGa2O4, epitaxially grown on c-plane sapphire via mist chemical vapor deposition. The films exhibit high crystalline quality, evidenced by relatively narrow rocking curves and atomically smooth surfaces. Hall measurements confirm stable p-type conduction with a hole mobility of 4.43 cm2 V−1 s−1 and a carrier concentration on the order of 1015 cm−3 in the optimized film at room temperature. By off-stoichiometrically tuning the Zn/Ga precursor ratio, we reveal that intrinsic p-type behavior originates from the antisite defect, establishing cation disorder as an important mechanism governing carrier polarity. Comprehensive structural, optical, electrical, and first-principles analyses indicate the interplay between defect chemistry and charge transport in spinel oxides. These results position ZnGa2O4 as a viable p-type UWBG semiconductor and introduce defect-controlled spinel oxides as promising materials for future high-power and extreme-environment electronics.