Mechanical stress control in GaN films on sapphire substrate via patterned nanocolumn interlayer formation

Abstract

Reduction of mechanical stress generated in GaN films is an important issue for production high quality templates for manufacturing more efficient light emitting diodes. One of the techniques to reduce such stress is a patterned nanocolumn interlayer formation at the vicinity of GaN/sapphire interface with the following GaN overgrowth. The aim of the present research is to prove the effectiveness of the described method in stress reduction and to find out the optimal configuration for patterned nanocolumn interlayer. Another aspect of the study is to investigate a possibility of self‐separation of the overgrown GaN layer by nanocolumns cracking while cooling. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effect of nano‐column properties on self‐separation of thick GaN layers grown by HVPE

“…In this study we analyzed the structure with a patterned nanocolumn interlayer, which consisted of a regular array of columns of conical shape with fill-factor of 30 to 40%. For numerical simulation, COMSOL software was used [1]. The results of the simulation (presented in Fig.…”

“…1 Introduction Nano-column buffer layers are recognized now as a promising way to produce free-standing GaN material. Recently, through the analysis of residual stress distribution we have shown that configuration of the pattern of nano-column structure (NCS) in the buffer layers might help to control the self-separation of the overgrown layers of GaN [1]. In this paper, self-separation of high-quality Hydride Vapor-Phase Epitaxy (HVPE) GaN layers grown on Metal-Organic Chemical Vapor Deposition (MOCVD) GaN/sapphire templates patterned with NCS is demonstrated.…”

Modeling of Threading Dislocation Density Reduction in AlN/Al2O3 Porous Heterostructure

“…The use of a porous layer for the subsequent growth of the film allows to reduce the level of thermoelastic stresses in the film occurring when the heterostructure is cooled after the growth process is completed [9,10]. In overall, thermoelastic stresses have a great impact, since they can control the evolution of defect structure in the process of heterostructure growth at high temperatures [11][12][13][14].…”