A High Quantum Efficiency Narrow-Band UV-B AlGaN p-i-n Photodiode With Polarization Assistance

Qianyu Hou,Rong Zhang,Haifan You,Youdou Zheng,Dunjun Chen,Hui Guo,Danfeng Pan,Pengfei Shao,Hai Lu,Qing Cai,Le Yu

doi:10.1109/jphot.2021.3086855

Qianyu Hou, Rong Zhang + Show 9 more

Open Access

https://doi.org/10.1109/jphot.2021.3086855

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Abstract

We designed and fabricated narrow-band UV-B AlGaN p-i-n photodiodes (PDs) with a full-width at half-maximum (FWHM) of 8 nm by optimizing the Al composition and thickness of the AlGaN layers. To improve the photoelectric response of the narrow-band PDs, a polarization electric field with the same direction with the applied bias field was introduced to the absorption layer by adjusting the Al composition ratio between the p-type AlGaN layer and i-type AlGaN absorption layer. The polarization enhanced narrow-band PD exhibited a higher external quantum efficiency (EQE) of 82% than the conventional one with an EQE of 67%. Meanwhile, a low dark current density of 1.7 nA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and four orders of magnitude UV-visible rejection ratio were achieved for the enhanced narrow-band PDs with a maximum photocurrent responsivity of 202 mA/W at 304 nm.

Highlights

Ultraviolet photodiodes (PDs) have multitudes of military and civilian applications such as flame detection, astronomical studies, ozone monitoring, and ultraviolet imaging [1]–[6]
We proposed and fabricated back-illuminated narrow-band UV-B AlGaN p-i-n PDs with a response window around 305 nm, which can realize the detection and identification of specific fuel components without using additional optical filters
For the polarization enhanced PD, the electric field spike has been mitigated at the junction of the p-AlGaN/i-Al0.3Ga0.7N layer, and electric field intensity in the p-type Al0.15Ga0.85N layer has dropped precipitously as compared with the conventional counterpart

Summary

Introduction

Ultraviolet photodiodes (PDs) have multitudes of military and civilian applications such as flame detection, astronomical studies, ozone monitoring, and ultraviolet imaging [1]–[6]. There still need more research about the design and optimization of AlGaN p-i-n photodiodes, especially for the UV-B narrow-band PDs with higher EQE for the detection and identification of specific fuel components. We proposed and fabricated back-illuminated narrow-band UV-B AlGaN p-i-n PDs with a response window around 305 nm, which can realize the detection and identification of specific fuel components without using additional optical filters. This was achieved by adjusting the Al composition and the thickness of the AlGaN layers.

Device Structure Design

Simulation Results

Device Fabrication

Results and Discussions

Conclusions