Porous Gallium Nitride Generated by Electroless Etching: Morphology, Optical Properties, and Sensing Applications

Abstract

In addition to characterization, several possible applications for porous GaN have been explored. Currently, because there is not a route for the growth of bulk GaN, GaN films must be grown heteroepitaxially. Substrates for GaN growth are not ideal, and introduce strain and defects. Porous GaN has been studied as an alternative substrate for high-quality epitaxial GaN film growth, and has shown modest improvement in crystal quality over conventional substrates. Additionally, porous GaN has been functionalized for use as a surface enhanced Raman spectroscopy (SERS) substrate by solution-based electroless deposition and vacuum evaporation of Ag and Au. SERS enhancement factors up to 10 8 have been observed for Ag-coated porous GaN, allowing the spectroscopic detection of trace amounts of analytes. The advantages of using porous GaN as a SERS substrate are the simplicity of substrate preparation and the consistency of the SERS response across the substrate. Ongoing studies are focused on using the innate properties of crystalline GaN and the high surface area inherent to the porous film as conductivity or hydrogen sensors.