Epitaxial growth of (0001) oriented porous GaN layers by chemical vapour deposition
LEDs with enhanced light extraction efficiency and sensors with improved sensitivity have been developed using porous semiconductors. Here, the growth of porous GaN epitaxial layers oriented along the  crystallographic direction on Al2O3, SiC, AlN and GaN substrates is demonstrated. A lattice mismatch between the substrate and the porous GaN layer directly affects the structure and porosity of the porous GaN layer on each substrate. Deposition of unintentionally doped n-type porous GaN on non-porous p-type GaN layers allows for the fabrication of high quality rectifying p–n junctions, with potential applications in high brightness unencapsulated GaN-based light emitting diodes and high surface area wide band gap sensor devices.