Coexisting multi-valence states of doped Ta into β-Ga2O3 films on B-doped mono-diamond to achieve high performance heterojunction detector

Ga2O3, as an ultra-wide bandgap semiconductor, has promising applications, e.g. solar-blind ultraviolet detectors, but is hindered by issues related to thermal conductivity and the P-type doping method. This study prepared P-N heterojunction via Ta-doped /3-Ga2O3 films on B-doped mono-diamonds. We found that the multivalence states of doped Ta coexisted in /3-Ga2O3 films, leading to a transmittance over 90 % caused by the formation of Ta2O5. Moreover, the dark current was four orders of magnitude higher than the intrinsic /3-Ga2O3 film, which was attributed to the Ga3+ being replaced by Ta5+. The B-doped mono-diamond exhibited a high carrier concentration of 5.08 x 1018 cm-3 and a low resistivity of 5.92 x 10-3 Omega cm due to the C4+ being replaced by B3+. The Ta-doped /3-Ga2O3/B-doped mono-diamond heterojunction detector exhibited excellent photoelectric properties with a high responsivity of 64 mA/W at +10 V bias voltage, providing a novel approach for solving the /3-Ga2O3/diamond challenge to realize high-performance detectors.