Effect of Substrate Surface Finish and Proximity Distance on Compositional Shift of InGaAsP Metal–Organic Vapor Phase Epitaxy in a High-Speed-Rotation Multiple-Substrate Reactor

Abstract

Shift of photoluminescence (PL) wavelengths toward shorter wavelengths (blue shift) in a specific area of InGaAsP quaternary epitaxial layers, grown in a high-speed rotating-disk type metal–organic vapor phase epitaxy (MOVPE) reactor, was found to be a deteriorative factor of PL wavelength uniformity in the epitaxial layers. Experiments were performed to generate a blue shift of PL wavelength, with two mirror-polished substrates placed in adjacent positions in the wafer carrier. Analysis of compositional distribution over 61 points was performed in InGaAsP/InP epitaxial layers with band gap corresponding to the 1310 nm PL wavelength. From this analysis, it was found that the blue shift of PL wavelength was dependent on the compositional shift of group V elements. In addition, the effect of substrate surface finish (mirror-polished or as-etched) was found to be a major cause of the compositional shift of group V elements. We found that, as the proximity distance between adjacent substrates was increased, there existed a critical proximity distance at which the blue shift disappeared.