Growth of in_0.5ga_0.5p on gaas by lpe: The influence of growth temperature and lattice mismatch on photoluminescence

InGaP epilayers were grown on (100) GaAs substrate by liquid phase epitaxy (LPE). Four different growth temperatures, 800, 750, 710 and 700degC were studied. We found that the lattice match condition for growth-homogeneous epitaxial layers relaxed at 800degC, and shrank with decreasing growth temperatures. As to the 700degC growth temperature, the growth melts were difficult to wipe off the substrate and no homogeneous epilayers could be obtained. The photoluminescence (PL) intensity of the growth layers depended on both the lattice match condition and the growth temperature. The defect-related PL peaks, at 39 and 37 meV below the band edge, were observed in most of the layers grown at 800 and 750degC, respectively. In a layer grown at 710degC, the defect-related subpeak became broad and dominated the PL spectrum. With a growth temperature of 750degC and a lattice mismatch (Δa^⊥a_s) of 0.2%, the InGaP epitaxial layers showed a mirror-like surface morphology, the strongest PL intensity, the narrowest PL FWHM (6 meV at 17 K) and a minimal defect-related PL subpeak.