Journal of Crystal Growth, Vol.230, No.3-4, 438-441, 2001
Chemical mapping of InGaN MQWs
High power LEDs fabricated from InGaN/GaN layers have received much research interest. Hence. in this paper we identify structural and chemical defects resulting from the epitaxial growth of these layers, which directly effect the performance of the device. TEM, annular dark field imaging (ADF), energy filtered TEM (EFTEM) and X-ray mapping were used to study multiple quantum wells structures capped with it p-type GaN layer. TEM and ADF studies of the samples show a number of V-defects which are roughly 100-200 nm apart along the MQW. Each V-defect incorporates a pure edge (b = 1/3 <1 1 (2) over bar 0 >) dislocation, which runs through the apex of the V-defect up to the free surface. These V-defects contain GaN with no InGaN layers, suggesting that the capping layer has filled in the open V-defects.
Keywords:growth models;planar defects;metalorganic chemical vapor deposition;quantum wells;semiconducting III-V materials;light emitting diodes