Phase separation and gap bowing in zinc-blende InGaN, InAlN, BGaN, and BAlN alloy layers

• Published in: Physica. E, Low-dimensional systems & nanostructures Vol. 13; no. 2; pp. 1086 - 1089
• Main Authors: Teles, L.K, Furthmüller, J, Scolfaro, L.M.R, Tabata, A, Leite, J.R, Bechstedt, F, Frey, T, As, D.J, Lischka, K
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2002
• Subjects: BAlN; BGaN; InAlN; InGaN; Phase separation; InGaN; InAlN; BGaN; Phase separation; BAlN
• ISSN: 1386-9477; 1873-1759
• DOI: 10.1016/S1386-9477(02)00309-0

We present first-principles calculations of the thermodynamic and electronic properties of the zinc-blende ternary In x Ga 1− x N, In x Al 1− x N, B x Ga 1− x N, and B x Al 1− x N alloys. They are based on a generalized quasi-chemical approximation and a pseudopotential-plane-wave method. T– x phase diagrams for the alloys are obtained. We show that due to the large difference in interatomic distances between the binary compounds a significant phase miscibility gap for the alloys is found. In particular for the In x Ga 1− x N alloy, we show also experimental results obtained from X-ray and resonant Raman scattering measurements, which indicate the presence of an In-rich phase with x≈0.8. For the boron-containing alloy layers we found a very high value for the critical temperature for miscibility, ∼9000 K , providing an explanation for the difficulties encountered to grow these materials with higher boron content. The influence of a biaxial strain on phase diagrams, energy gaps and gap bowing of these alloys is also discussed.