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

摘要

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 GaAs_(1-x)N_x(x~0.03). The source gases for Ga, As, and N are trimethylgallium ((CH_3)_3Ga), arsine (AsH_3), and ammonia (NH_3), 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 NH_3/(NH_3+AsH_3) 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.