Effects of Ga- and Sb-precursor chemistry on the alloy composition in pseudomorphically strained GaAs_(1-y)Sb_y films grown via metalorganic vapor phase epitaxy

摘要

GaAs-based multiple quantum well (MQW) heterostructures comprised of metastable alloys such as GaAs_(1-y)Sb_y-GaAs_(1-z)N_z have potential for realizing high-performance and low temperature-sensitivity lasers in the 1.55 μm wavelength region. However, strain-induced 'lattice-latching' and Sb-surface segregation effects limit the Sb-mole fractions in the pseudomorphically strained GaAs_(1-y)Sb_y layers to y ≤ 0.2. The effect of Ga- and Sb-precursor chemistry and the growth temperature on the Sb-incorporation efficiency in strain-relaxed and strained, pseudomorphic GaAs_(1-y)Sb_y films was studied using metalorganic vapor phase epitaxy. Both trimethyl- and triethyl-gallium (TMGa and TEGa) and trimethyl- and triethyl-antimony (TMSb and TESb) were used as Ga- and Sb-precursors, in four different source combinations, with arsine. The Sb-mole fraction in the strained GaAs_(1-y)Sb_y films was found to be lower than that in the relaxed films for all of the precursor chemistries. The highest Sb-incorporation rates were found with the TEGa-based growth with strained-layer compositions up to y～0.48 being obtained for the growth conditions employed. The results were discussed in terms of the strain-related thermodynamic effects and the chemical kinetics of precursor surface decomposition for the different precursor chemistries.