Polarization-Assisted AlGaN Heterostructure-Based Solar-Blind Ultraviolet MSM Photodetectors With Enhanced Performance
Wenxin Li, Yifu Wang, Guangyang Gu, Fangfang Ren, Dong Zhou, Weizong Xu, Dunjun Chen, Rong Zhang, Youdou Zheng, Hai Lu
Abstract
In this work, a high-performance metal–semiconductor–metal solar-blind ultraviolet photodetector (UV PD) based on AlGaN heterostructure (AlGaNH) is fabricated. By utilizing the built-in polarization effect, a highly conductive two-dimensional electron gas channel is induced at the Al <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{0}.{65}}$ </tex-math></inline-formula> Ga <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{0}.{35}}\text{N}$ </tex-math></inline-formula> /Al <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{0}.{4}}$ </tex-math></inline-formula> Ga <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{0}.{6}}\text{N}$ </tex-math></inline-formula> heterointerface. The AlGaNH PD exhibits a high peak responsivity of 3.42 A/W at 270 nm, which is considerably higher than that of the control AlGaN PD without polarization enhancement. Meanwhile, the device exhibits a low dark current of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.2\times 10^{-{11}}$ </tex-math></inline-formula> A at 10 V bias, which results in a high photo-to-dark current ratio exceeding <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7\times 10^{{3}}$ </tex-math></inline-formula> even when the incident light intensity is as low as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 5 \mu \text{W}$ </tex-math></inline-formula> /cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . A theoretical analysis of gain mechanism reveals that the high responsivity can be attributed to the longer lifetime and shorter drift time of the photogenerated carriers within the heterointerface channel. A high specific detectivity can be achieved at elevated temperatures, while a fast response speed can be maintained even at low incident light intensity. This work provides a viable approach to enhance the detection performance of AlGaN-based solar-blind PDs.