Influence of UV Light-Assisted Annealing on Optical Properties of InGaN/GaN Heterostructures Grown by MOVPE

The influence of ultraviolet light-assisted annealing on the optical properties of InGaN/GaN single quantum wells (SQW), and thick single and double heterostructures (SH, DH) was investigated. It was shown that annealing promotes an increase of the photoluminescence (PL) intensity from the active layers of the SQW and double heterostructures by as much as one order of magnitude. This is effected mainly by a diminishing of the defect concentration and a smoothing of the potential fluctuations in the upper cladding layer. The operating temperature of the DH lasers was lifted from 220 up to 300 K after annealing. Using nitrogen laser irradiation during annealing led both to a PL efficiency increase and to a phase separation in the SH with a thick active layer.