Enhancing Carrier Transport and Injection of Ga₂O₃ Deep-Ultraviolet Schottky Photodiode by Introducing Impurity Energy Level

Abstract

In this letter, a Ti/Sn-Ga2O3/Ni Schottky photodiode device was achieved by a rarely-reported PECVD technology. Benefitting from the introduction of Sn impurity energy level, which provides extra paths for carriers’ generation and helps create a stronger built-in electric field to facilitate carriers’ separation, the carrier transport and injection efficiency of device are collaboratively enhanced. Under 254 nm deep-ultraviolet (DUV) light, the device displays an ultrahigh responsivity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}{)}$ </tex-math></inline-formula> of 3508A/W, outperforming the corresponding Ti/Ga2O3/Ni device (14.7 A/W) and many other Sn-doped Ga2O3 photodetectors (PDs). Meanwhile, the device exhibits the low dark current of −6.6pA/4.79nA (~720 rectification ratio) under dark conditions, together with a remarkable external quantum efficiency of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${1}.{72}\times {10} ^{{6}}$ </tex-math></inline-formula> %, an outstanding detectivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${4}.{9} \times {10} ^{{14}}$ </tex-math></inline-formula> Jones at 5 V bias under DUV illumination. Furthermore, the device can operate in self-powered mode with an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}$ </tex-math></inline-formula> of 100 mA/W as well, and this work demonstrates the huge potential of high-performance PECVD-grown elemental-doped Ga2O3 film-based PDs.