Cathodoluminescence and depth-profiling cathodoluminescence studies of interface properties in MOCVD-grown InGaN/GaN/sapphire structures: role of GaNbuffer layer

We report the results of room-temperature cathodoluminescence (CL) and of s canning CL and electron (SEM) microscopy of GaN/InGaN structure with a sing le InGaN quantum well on top. The structures were grown by MOCVD on sapphir e with Low-temperature (LT) GaN buffer. Depth-profiling CL investigations w ere used to identify the observed CL emissions, which show a complicated in -depth evolution. The influence of a LT GaN buffer on structural and optica l properties of GaN/sapphire interface in the structure is discussed. Our r esults show that inter-diffusion of Al from sapphire to the GaN buffer laye r takes place. A gradual improvement of film quality with increasing distan ce from interface is demonstrated. (C) 2001 Elsevier Science B.V. All right s reserved.