High rate photoelectrochemical etching of GaN and the use of patterned substrates for HVPE regrowth

High etching rates of HVPE GaN, up to 2 μm/min, have been achieved by photoelectrochemical etching to produce stripes which are 70–100 μm high. These wafers have been used as substrates for subsequent HVPE growth. The surface after the second growth was irregular and needed to be polished prior to defect density evaluation. The dislocation densities measured by the defect-selective etching were 2×107 cm−2 and 3×105 cm−2 in the stripe region and the low-dislocation-density lateral growth region, respectively. The low-dislocation-density regions formed stripes of about 10 μm.