Improvement of Porous GaN-Based UV Photodetector with Graphene Cladding

Furqan Khairi Mohammed,Fong Kwong Yam,Khi Poay Beh,Naser M Ahmed,Zainuriah Hassan,Asmiet Ramizy

doi:10.3390/app112210833

Furqan Khairi Mohammed, Fong Kwong Yam + Show 4 more

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https://doi.org/10.3390/app112210833

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Abstract

This work presents the role of graphene in improving the performance of a porous GaN-based UV photodetector. The porous GaN-based photodetector, with a mean pore diameter of 35 nm, possessed higher UV sensitivity, about 95% better compared to that of the as-received (non-porous) photodetector. In addition, it exhibits a lower magnitude of leakage current at dark ambient, about 70.9 μA, compared to that of the as-received photodetector with 13.7 mA. However, it is also highly resistive in nature due to the corresponding electrochemical process selectively dissolute doped regions. Herein, two types of graphene, derived from CVD and the electrochemical exfoliation (EC) process, were cladded onto the porous GaN region. The formation of a graphene/porous GaN interface, as evident from the decrease in average distance between defects as determined from Raman spectroscopy, infers better charge accumulation and conductance, which significantly improved UV sensing. While the leakage current shows little improvement, the UV sensitivity was greatly enhanced, by about 460% and 420% for CVD and EC cladded samples. The slight difference between types of graphene was attributed to the coverage area on porous GaN, where CVD-grown graphene tends to be continuous while EC-graphene relies on aggregation to form films.

Highlights

Graphene is best described as a single layer of carbon atoms arranged hexagonally on a flat two-dimensional (2D) plane
The graphene materials were cladded onto the surface of porous Gallium nitride (GaN) (Pr-GaN), where the overall product would be a UV-photodetector, and subsequently, their performances were evaluated
Pr-GaN had a higher exposed surface area for UV sensing, its performance was significantly improved with the integration of graphene, i.e., graphene/Pr-GaN heterojunction

Summary

Introduction

Graphene is best described as a single layer of carbon atoms arranged hexagonally on a flat two-dimensional (2D) plane. It is known as a zero-gap material with excellent electronic and thermal properties [1,2,3]. Graphene films of lower defects and thickness of monolayers can be grown on copper substrate using the CVD method [10,11,12,13] This method employs vacuum furnace and flow meters, as well as hydrocarbon precursors (e.g., methane) and hydrogen, in order to facilitate the necessary chemical reactions. Other alternatives have been explored as well

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