Heteroepitaxial β‐Ga2O3 on Conductive Ceramic Templates: Toward Ultrahigh Gain Deep‐Ultraviolet Photodetection

Abstract

AbstractThis article investigates the ultrahigh sensitivity and DUV photodetection capability of a hybrid oxide‐nitride stack comprising β‐Ga2O3 layers grown heterogeneously on a conductive ceramic crystal. The ceramic crystal, namely a TiN interlayer, which acts as a lattice template, was heteroepitaxially grown on bulk MgO. Because β‐Ga2O3 is a monoclinic phase crystal, it is conjectured that its nucleation and growth process on cubic phase TiN is entropic in nature, whereby the two unit cell configurations of the β‐Ga2O3 crystal, exhibiting rotational twin domains, grew alternately side by side in a semiperiodic manner on TiN while maintaining a single crystal phase. This film formation mechanism contributed to the introduction of additional defects in the β‐Ga2O3 lattice (Taylor's dislocations in addition to growth‐induced vacancies). The fabricated DUV photodetectors based on the resulting metal‐semiconductor junction heterodiodes exhibited an average peak spectral responsivity of 276.72 A W−1 and fast decay constants in the order of 500 ms in the ultraviolet‐C regime, with true solar‐blind characteristics manifested by ultraviolet‐to‐visible rejection ratios of up to 2 × 103 and illuminating power density of around 70 μW cm−2. The crystallographic orientation relationships between the TiN and β‐Ga2O3 crystals, as well as the lattice fit and dislocation types, are revealed and examined.