Photoluminescence study on threading dislocation in GaN revealed by selective photoelectrochemical etching

Selective etching was studied between the crystalline GaN and its dislocations by controlling the KOH concentration and the ultraviolet photon intensity in photoelectrochemical (PEC) etching. The PEC etching rate of GaN is governed by the density of photo-generated carriers and the direct chemical reaction between GaN and the electrolyte. The dislocation is more chemically reactive than crystalline GaN, whereas crystalline GaN has a higher density of the photogenerated minority carrier than the threading dislocation. 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 and the peak at 3.35 eV is attributed to the threading dislocation.