Thermodynamic analysis of vapor-phase epitaxial growth of GaAsN on Ge

In this paper, we use thermodynamic analysis to determine how the nitrogen (N) ratio in the source gases affects the solid composition of coherently grown GaAs1−xNx(x∼0.03). The source gases for Ga, As, and N are trimethylgallium ((CH3)3Ga), arsine (AsH3), and ammonia (NH3), respectively. The growth occurs on a Ge substrate, and the analysis includes the stress from the substrate–crystal lattice mismatch. Calculation results indicate that to have just a few percent N incorporation into the grown solid, the V/III ratio in the source gases should be several thousands and the input-gas partial-pressure ratio NH3/(NH3+AsH3) should exceed 0.99. We also find that the lattice mismatch stress from the Ge substrate increases the V/III source–gas ratio required for stable growth, whereas an increase in input Ga partial pressure ratio has the opposite effect.

► We performed thermodynamic analysis for coherent growth of GaAsN.
► A system using TEG, AsH3, and NH3 as the gaseous sources was analyzed.
► Incorporation of a few percent N into a solid needs an NH3/(NH3+AsH3) ratio of over 99% in input gas.
► The lattice constraint from the substrate suppresses the incorporation of nitrogen.
► Higher input Ga partial pressure ratio enhances the stable growth with a few percent of N.