Ultrahigh Gain at Low Bias Achieved in Homoepitaxial Ga2O3 Schottky Photodiode With Low Dark Current

Ga2O3-based solar-blind photodetectors (SBPDs) with typical Schottky structure usually exhibit low responsivity and rapid saturation as reverse bias increase in the lack of avalanche gain. In this study, large-area photosensitive Ga2O3 single-crystalline films were homoepitaxially grown by MOCVD, enabling the fabrication of high-performance SBPDs. At a low bias of -5 V, the device exhibits an ultrahigh photoresponsivity of 27.5 A/W and a photo-to-dark current ratio of $2.4\times 10^{{5}}$ with an ultralow dark current of $3.74\times 10^{-{8}}$ A/cm2, superior to most similar Ga2O3 SBPDs reported to date. Furthermore, without sacrificing the response speed (t $_{\text {r}} =100$ ns, t $_{\text {d}} = 240.5~\mu $ s), the device attained a peak external quantum efficiency of $1.5\times 10^{{4}}$ %. This stems from the ultrahigh photoconductive-like gain caused by significant mobility differences of photogenerated carriers under reverse bias in high-quality Ga2O3 homo-epilayer.