Defect-related transitions in luminescence of InAlAs on InP

A study of photoluminescence (PL) of InAlAs grown on InP by molecular beam epitaxy was performed in a wide range of temperatures and excitation intensities. A novel defect-related transition has been observed for the first time by 120-180 meV below the near band edge PL line of InAlAs. The novel band appears in the spectra only in a limited range of temperatures around 50-160 K. In that temperature range the band may dominate in the PL spectrum. The characteristics of the band show that it is related to recombination via deep centres located in potential wells created by the alloy clustering. We show that by establishing quasi-stoichiometric conditions on the growth surface we were able to grow layers which show virtually zero intensity of the defect-related transitions and luminescence efficiencies by 1-2 orders of magnitude greater than that in the samples grown under standard conditions.