Microstructural Investigation of Bilayer Growth of In- and Ga-Rich InGaN Grown by Chemical Vapor Deposition

Abstract

Epitaxial InGaN with an In content of up to 89% was grown on a GaN template on a sapphire substrate using metalorganic chemical vapor deposition. The grown layer showed a bilayered structure of In-and Ga-rich InGaN parallel to the growth plane, as confirmed by both x-ray diffraction and electron microscopy. High-angle annular dark-field images revealed that pyramidal Ga-rich InGaN had formed on the top of the In-rich InGaN layer with an abrupt interface. Nucleation of the In-rich InGaN was believed to be related to threading dislocations stemming from the GaN buffer layer.

Indium Incorporation Induced Morphological Evolution and Strain Relaxation of High Indium Content InGaN Epilayers Grown by Metal–Organic Chemical Vapor Deposition

“…Furthermore, previous literature mainly focused on MBE-grown high In content ( x > 0.2) InGaN, which is surface kinetics-controlled and takes advantage of the low growth temperature ( T g ) to avoid phase separation and decomposition . While for metal–organic chemical vapor deposition (MOCVD) grown high In content InGaN epilayers, which is governed by a diffusion process and differs from MBE, progress has often been limited by significantly degraded crystal quality due to the deficient ammonia cracking (<5% at 700 °C), making MOCVD less attractive for growing higher In content InGaN and very few works have been dedicated to the morphological evolution and strain relaxation of such InGaN of relatively higher In contents grown by MOCVD. − However, MOCVD is still a leading industrial technique for the growth and fabrication of GaN-based optoelectronic devices. One the other hand, the nonlinear optical properties of high In content InGaN alloy, such as second harmonic generation , and optical rectification, , have attracted special interest because of its promising utilization and relevance in making optical switching and optical telecommunication devices. ,− Therefore, a deeper investigation of In incorporation kinetics, strain relaxation, and resultant morphological evolution of InGaN with high In content grown by MOCVD is currently important and necessary.…”

High-Resolution Electron Microscopy of Semiconductor Heterostructures and Nanostructures

“…For AlGaN, composition modulation [136], phase-separated domains [144] sometimes having tunnel defects and associated dislocations with erratic behaviors [145] have also been measured. On the other hand, surface-grown InGaN thin films showed bilayered structures of In-and Ga-rich InGaN parallel to the growth plane [146]. For InGaN/GaN and AlGaN/GaN, most of these kinds of studies focused on the presence of V-defects, atomic fluctuations or clustering, and electron beam damage in multi-quantum wells [147,148].…”