Comparative study of structural properties and photoluminescence in InGaN layers with a high In content

Rutherford backscattering and channeling spectrometry (RBS), photoluminesce nce (PL) spectroscopy and transmission electron microscopy (TEM) have been used to investigate macroscopic and microscopic segregation in MOCVD grown InGaN layers. The PL peak energy and In content (measured by RES) were mapp ed at a large number of distinct points on the samples. An indium concentra tion of 40%, the highest measured in this work, corresponds to a PL peak of 710 nn strongly suggesting that the light-emitting regions of the sample m e very indium-rich compared to the average measured by RES. Cross-sectional TEM observations show distinctive layering of the InGaN films. The TEM stu dy further reveals that these layers consist of amorphous pyramidal contras t features with sizes of order 10 nm The composition of these specific cont rast features is shown to be In-rich compared to the nitride matrix.