Interface recombination and photoluminescence efficiency of thick (< 3 μm) InGaAs prepared by LPE with InAs-enriched composition

In0.97Ga0.03As with a room temperature energy gap of 0.375 eV, corresponding to the fundamental hydrocarbon absorption band at 3.32 μm, was prepared by liquid phase epitaxy (LPE). The epitaxial layer thickness was consistent with a diffusion-limited growth mechanism. Since gallium was the minor constituent in the indium-based melt, growth of the InGaAs epitaxial layer was found to be limited by the rate of arrival of gallium at the melt-solid interface. A value of DGa=3×10-4 cm2 s-1 (597.5°C) found for the gallium diffusion coefficient in the melt. The LPE grown material was characterized as a function of layer thickness using photoluminescence spectroscopy. The peak photoluminescence emission intensity was found to increase with epitaxial layer thickness. This was correlated with a reduction in interface recombination at the InGaAs/InAs heterojunction. The improved surface morphology observed in thicker layers was thought to be related to a decreased threading dislocation density in the thicker samples. In the extrinsic p-type InGaAs material a value of 5.2×10-8 s was calculated for the 80 K radiative lifetime.