A Cathodoluminescence Study of InGaN/GaN Multiple Quantum Well and N Type GaN Structures

摘要

A systematic study of the V-pits in 4 periods of InGaN/GaN multiple quantum well structure (MQW) and defects in n type GaN is investigated by room temperature cathodoluminescence. These MQWs were fabricated on a sapphire substrate by using metal organic chemical vapor deposition. The crystal quality is affected by the lattice mismatch between GaN and the sapphire substrates which results in the generation of a high threading dislocation (TD) density in GaN. It is believed that V-defects originate at the InGaN/GaN interface and may cause non-radiative recombination centers thus reducing the quantum efficiency of the structure. The optical emission from these defects is discussed in this paper. The density of V-defects observed in monochromatic CL images is compared to the TD density in n type GaN sample.