Compositional inhomogeneity of liquid phase epitaxial InGaPAs layers observed directly in photoluminescence

Data are presented on photopumped rectangular samples indicating that immediately (⩽18 ms) after the LPE growth of In1−xGaxP1−zAsz on InP begins a thin ∼100-Å quaternary layer is deposited of lower energy gap (ΔE∼15 meV) than that of the succeeding LPE thicker layer that grows later near diffusion-limited quasiequilibrium conditions. This conclusion is based on a comparison made between the photoluminescence spectra from a single quaternary layer deposited in ∼1 s of uninterrupted growth and that from a composite InGaPAs layer consisting of nine successive depositions of the initial thin layer.