OPTICAL CHARACTERIZATION OF GAN AND RELATED MATERIALS

Recent experimental results on optical properties of GaN and related m aterials are discussed. Photoluminescence data of free excitons for su fficiently pure GaN samples demonstrate the dominance of excitonic rec ombination well above room temperature. Transient PL data give a radia tive lifetime of about 200 ps for the A-exciton at 2 K in strain-free samples. A corresponding value of about 2 ns at room temperature is ex trapolated. Radiative lifetimes for bound excitons are measured as abo ut 250 ps for shallow donors and about 1.5 ns for shallow accepters. P hotoluminescence spectra from the 2D electron gas at a GaN/AlGaN heter ointerface are also demonstrated. (C) 1997 Elsevier Science Ltd.