Microstructural Characterization of In-platelets with High In Composition in InGaN/GaN Multiple Quantum Wells

Abstract

An increase in the concentration of In (indium) platelets with a high In composition in InGaN/GaN multiple quantum wells (MQWs) can deteriorate the properties of GaN-based light emitting diodes (LEDs) and laser diodes (LDs) considerably. This paper reports a microstructural characterization of In platelets with In-rich segregations in InGaN/GaN MQWs. GaN layers and InGaN/GaN MQWs were grown by using metal-organic chemical vapor deposition (MOVCD). The microstructural properties of the In platelets were examined by using transmission electron microscopy. The crystal structure and the elemental compositions of the In platelets were analyzed by both a fast Fourier transform analysis simulated from a high-resolution TEM image and electron energy loss spectroscopy. A large number of defects, such as dislocations, stacking faults and precipitates, were observed in the InGaN/GaN MQWs. In particular, many In platelets, >30 nm in size, were formed with a high In composition (≈50%) because the In composition within the InGaN well was absorbed into the In platelets. The In platelets were the result of phase separation of the InGaN/GaN MQWs and were composed of a zinc-blende structure, which is in contrast to the wurtzite structure of the normal InGaN well.