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 of2.4× 10^5with an ultralow dark current of3.74× 10^-8A/cm2, superior to most similar Ga2O3 SBPDs reported to date. Furthermore, without sacrificing the response speed (tᵣ =100ns, td = 240.5~μs), the device attained a peak external quantum efficiency of1.5× 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.