PHOTOLUMINESCENCE CHARACTERIZATION OF INGAP/GAAS HETEROSTRUCTURES GROWN BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION

Growth conditions of metalorganic chemical vapor deposition have been investigated for the purpose of obtaining abrupt InGaP/GaAs interfaces. Photoluminescence (PL) spectra of InGaP/ GaAs: quantum wells (QWs) are used to characterize these interfaces. The conventional gas switching sequence, i.e., simultaneously switching pn group-III and -V gases, is found to provide only a broad peak at wavelengths longer than those of near-band-edge emissions from GaAs in the PL spectrum of the InGaP/GaAs QW. PL studies using QWs having an AlGaAs barrier, for example, AlwGaAs/GaAs/InGaP and InGaP/GaAs/AlGaAs, show that the GaAs-on-InGaP interface is responsible for this broad peak. A novel gas switching sequence where group-III gas is switched on first results in sharp peaks corresponding to 5.7- and 2.8-nm-thick wells in the PL spectrum of InGaP/GaAs QW. Preflow of TMGa on InGaP surface is effective in suppressing the substitution of P atoms in InGaP to As atoms at the GaAs-on-InGaP interface. (C) 1995 American Institute of Physics.