Growth of strained GaAs1−ySby layers using metalorganic vapor phase epitaxy

The growth of pseudomorphically strained GaAs1−ySby layers with high Sb-mole fractions of y⩾0.35 are desired on GaAs substrates for making lasers and detectors in the mid-infrared range. The effect of gas-phase precursor chemistry on the strained-layer Sb-incorporation efficiency in metalorganic vapor phase epitaxy (MOVPE) was determined using four combinations of ethyl- and methyl-Ga and Sb precursors. The Sb-mole fractions in the strained GaAs1−ySby layers were found to be lower than those in relaxed films due to the strain-induced ‘lattice-latching’ effects. The Sb-mole fraction in the strained GaAs1−ySby layers decreased with the increasing AsH3/Ga ratio for all the precursor chemistries. Higher Sb-incorporation efficiencies were observed for the ethyl-Ga chemistries. The experimental results were discussed in terms of lattice-latching effects, Sb-segregation phenomena and different decomposition kinetics for various precursor chemistries.