Imaging of High-Angle Annular Dark Field Scanning Transmission Electron Microscopy and Microscopy Studies of GaN-based Light Emitting Diodes and Laser Diodes

Abstract

Atomic-resolution high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) has been used to the structural and compositional analysis of materials. The first part of this paper is a review of our recent HAADF-STEM investigations, which comprise physics to understand its imaging, and illustration of artifacts in images and imaging process. Next, we present our investigations of the multiple InGaN/GaN quantum wells and the strained AlGaN/GaN superlattice cladding in InGaN-based light emitting diodes or laser diodes, which have been performed by HAADF-STEM, high-resolution field-emission scanning electron microscopy, and high-resolution transmission electron microscopy. The observation of ultra-high density InGaN quantum dots is also shown.