Solar-blind ultraviolet photodetectors with thermally reduced graphene oxide formed on high-Al-content AlGaN layers

Bhishma Pandit,Jaehee Cho

doi:10.1063/5.0072093

Abstract

Solar-blind deep-ultraviolet (UV) photodetectors (PDs) with high responsivity and fast response have attracted significant attention in environmental, industrial, biological, and military applications. AlGaN is a representative semiconductor material in the field of solar-blind detection; semiconductor performance can be accelerated by combining it with high-transparency, high-stability contact electrode materials. In this study, solar-blind deep-UV metal–semiconductor–metal (MSM) PDs were fabricated based on two-dimensional reduced graphene oxide (rGO) contacts formed on various high-Al-content AlGaN semiconductors. A low dark current in the order of a few picoamperes and a fast photoresponse time of a few tens of milliseconds were confirmed. The investigation of the effects of front- and back-side illumination showed that the photocurrents and corresponding responsivities of the PDs drastically improved under back-side illumination. In detail, the peak locations of the responsivity–wavelength curves were downshifted from 290 nm with a responsivity of 0.0518 A/W for the rGO/Al0.5Ga0.5N MSM PD to 250 nm with a responsivity of 0.0113 A/W for the rGO/Al0.7Ga0.3N MSM PD under back-side illumination. These results indicate that rGO contacts on AlGaN provide a viable approach for developing solar-blind deep-UV PDs.

Highlights

Scitation.org/journal/adv centers, which directly influences the electrode–semiconductor interfacial properties and the generation and collection efficiency for photodetection.[18,19,20]
Employing the interdigitated metal-finger electrode structure on an MSM PD raises the issue of transparency.[21,24]
The photodetection properties, including spectral and temporal responses, of the samples were sequentially investigated and compared under both front- and back-side illumination conditions. 1.1-μm-thick AlGaN epitaxial layers with various Al mole fractions were grown by metalorganic chemical vapor deposition (MOCVD) on 2-in. sapphire substrates and used for the fabrication of photodetectors

Summary

Introduction

Scitation.org/journal/adv centers, which directly influences the electrode–semiconductor interfacial properties and the generation and collection efficiency for photodetection.[18,19,20]. MSM PDs that employed reduced GO (rGO) interdigitated finger electrodes and AlGaN semiconductors with an Al mole fraction exceeding 50%. AlN, respectively; x is the Al mole fraction; and Eb = 1.0 is the bowing parameter.[30] This equation provides the bandgap energies of 4.55, 4.84, 5.15, and 5.48 eV for the AlxGa1−xN layers with x

Results

Conclusion