Cathodoluminescence characteristics of InGaN/GaN quantum wells grown by MOCVD

Phase separation and In segregation in InGaN/GaN quantum wells (QWs) grown by metalorganic chemical vapor deposition (MOCVD) were studied by cathodolu minescence (CL) imaging and spectroscopy. The spatial homogeneity of optica l properties in InGan/GaN QW was studied. It is found that the CL images ta ken at different wavelengths show very little difference for the In-low QW, while some parts are complementary for the In-low QW. This result strongly suggests that the additional intensity fluctuation which appears with incr easing indium composition is due to phase separation in the InGaN layers. E specially, In0.16Ga0.84N quantum wells with In compositional non-uniformity and a small number of structural defects originating at the InGaN/GaN inte rface showed sharp and intense InGaN emission in CL spectroscopy. Increasin g the In composition caused surface roughness in the InGaN layer and the fo rmation of stacking faults/dislocations originating at InGaN/GaN interface. This resulted in a reduction of the InGaN emission peak intensity. (C) 200 1 Elsevier Science B.V. All rights reserved.