Optical Properties Characterization of InGaN/GaN near UV Photodetector with Surface Nano-Structure Fabricated by Nano-Imprinting

An InGaN/GaN-based photodetector with nano-structure on the surface is present. Surface nano-structure was formed by nanoimprint lithography (NIL) and reactive ion etching (RIE) techniques. The NIL technique and nano-structure etching by employing RIE were demonstrated in details. The nano-pattern was designed as regular triangles consisting of columns, whose diameter and period were around 105 and 210 nm, respectively. The height of nano-columns was around 66 nm. The photo-voltage of this type of photodetector had very good wave characteristics with 60° period, and it presented different waveform at different angles and wavelengths of incident light. The periodic characteristics took not only on minimum voltage but also peak voltage. We demonstrated this characteristic by employing Bragg formulation.