Growth and photoluminescence spectra of high-purity liquid phase epitaxial In0.53Ga0.47As

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Abstract
High-purity liquid phase epitaxial In0.53Ga0.47As has been grown on semi-insulating (100) InP:Fe substrates. The electrical characteristics of the layers were determined from Hall measurements. Different melt-baking schemes were used to improve the purity of the grown layers. It was found that the layers with the most desirable transport properties were obtained by a 20–40 h bakeout of the In melt followed by 20–60 h bakeout of In+InAs+GaAs under ultrapure H2 flow. Such layers were n-type with ND and NA∼1014 cm−3 and with μ300 K and μ77 K=9000 and 55 000 cm2/V s, respectively. Some of the as-grown layers were subsequently heat treated with an InAs proximity cap at 670 °C for 20 min under H2 flow. High-resolution photoluminescence measurements were performed with the as-grown and heat-treated layers at temperatures down to 4.4 K. The spectra were correlated with the growth conditions. Measurements at different temperatures and with varying excitation intensity helped to elucidate excitonic and impurity-related transitions. The most intense peaks at the highest energies arise from bound excitons. Carbon is usually not detected in the LPE crystals except those grown after 100 h or longer melt baking. The binding energy EA of carbon acceptors is 13.0±1.0 meV. Other acceptor-related transitions observed in the spectra are Zn with EA=28.0±1.0 meV and Si with EA=33.0±2.0 meV. An LO-phonon replica of the Zn-related transition was consistently observed with ℏwLO=32.0±1.0 meV. From our measurements it transpires that the 0 K band gap of In0.53Ga0.47As is ∼0.822 eV.

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