Influence of lattice constraint from InN and GaN substrate on relationship between input mole ratio and solid composition of InGaN during MOVPE

Thermodynamic analyses incorporating the contribution of lattice constraint from the substrates were carried out to understand the relationship between input In mole ratio and solid composition of stress-free InGaN, InGaN on GaN and InGaN on InN during metalorganic vapour phase epitaxy. The calculated results suggest that a compositionally unstable region is found at the InN-rich region for InGaN on GaN at high temperatures, while that for InGaN on InN can be seen at the GaN-rich region due to the lattice constraint from the substrate. These results imply that incorporating the contribution of lattice constraint is indispensable to predict the thermodynamic properties of such materials.