Vapor Phase Epitaxial Growth and Characterization of Ga_1-yIn_yAs_1-xP_x Quaternary Alloys

Epitaxial layers of Ga_1-yIn_yAs_1-xP_x alloys have been grown on GaAs substrates using an AsH₃-PH₃-Ga-In-HCl-H₂ chemical vapor deposition system. The influence of mole ratios Ga/(Ga+In) and P/(As+P) in the input gas stream on the alloy composition of epitaxial layers has been investigated. As for the group V elements, the deposition probabilities of As and P species in gas phase are approximately equal for small y, but As deposition appears to become dominant for large y. As for group III elements, Ga is always incorporated more preferentially than In. The lattice constant of the quaternary alloys is ascertained to obey Vegard's law and the composition dependence of the bandgap, obtained from photoluminescence measurements, is compared with an interpolation formula, derived by use of the bowing parameters of ternary alloys.