Experimental Evaluation of the Response of AlGaN/GaN UV Photodetectors With Square and Hexagonal Nanohole Arrays

This study presents an experimental investigation of AlGaN/GaN ultraviolet photodetectors (UV PDs) incorporating square and hexagonal nanohole arrays, aiming to enhance the devices’ optical and electrical performance. The nanoholes were fabricated on the AlGaN surface using an etching process to improve light trapping and absorption across the UV spectrum. The study systematically compares the performance of square and hexagonal nanohole arrays against conventional planar devices. The results show that nanohole arrays significantly enhance UV photodetection, with square and hexagonal nanohole arrays exhibited superior responsivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 2 \times 105$ </tex-math></inline-formula> A/W at 365 nm, outperforming planar devices. Additionally, the hexagonal arrays demonstrated a higher UV/visible rejection ratio of 12, compared to 10 for square arrays and 4 for planar devices. This performance improvement is attributed to the optimized surface-to-volume ratio and light coupling efficiency provided by the nanostructures. While an increase in response times was observed in nanostructured devices, the overall enhancement in responsivity indicates the strong potential of nanohole arrays for improving UV PD efficiency. These findings demonstrate the feasibility of using nanostructuring techniques to advance wide bandgap semiconductor PDs.