Aligned Mesopore Arrays in GaN by Anodic Etching and Photoelectrochemical Surface Etching

Abstract

Aligned mesopore arrays have many potential applications in bulk heterojunction photovoltaics, sensors, and photocatalysts. In this study, vertically aligned mesopores in n-doped GaN thin films were fabricated using an anodic etch procedure in nitric acid. The resulting porous structure remains monocrystalline and is highly conductive. After etching, a low-porosity nucleation layer was observed on the surface, and was subsequently removed with a UV-assisted anodic etch to expose the pores. Removal of the surface layer allows diffusion from the pores, suitable for sensitized photovoltaics and chemical sensors. Extremely fast etching rates of over 2 μm/s were recorded, with indication that hole transport in the epilayer was limiting the reaction rate even in highly doped samples.