Photoluminescence Study on Threading Dislocation in GaN Revealed by Selective Photoelectrochemical Etching

Abstract

Selective etching was studied between the crystalline GaN and its dislocations by controlling the KOH concentration and the ult raviolet photon intensity in photoelectrochemical (PEC) etching. The PEC etching rate of GaN is governed by the density of photogenerated carriers and the direct chemical reaction between GaN and the electrolyte. The dislocation is more chemically reactiv e than crystalline GaN, whereas crystalline GaN has a higher density of the photogenerated minority carrier than the threading dis location. By using the selective etching method, the origin of photoluminescence (PL) from the near bandedge of crystalline GaN and dislocations could be clarified. The room-temperature PL peak at 3.41 eV is due to the emission from the crystalline GaN an d the peak at 3.35 eV is attributed to the threading dislocation.