Near-band gap absorption and photoluminescence of In0.53Ga0.47As semiconductor alloy

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Abstract
In this paper, the near-band-gap absorption and photoluminescence (PL) spectra of In0.53Ga0.47As liquid-phase epitaxial layers are reported. We observed, for the first time, the free exciton absorption peak in the transmission spectra and determined the exciton binding energy of 2±1 meV at 5 K for this alloy system. In low temperature PL spectra, a sharp peak (FWHM = 3∼16 meV) observed for all n-type (undoped, Si-doped, or Sn-doped) samples was assigned to be a donor-to valence band transition. The donor ionization energy was determined to be ∼10 meV. A weak second peak at ∼20 meV below the donor-to-band transition with FWHM = 15∼20 meV was also seen in these samples. It is likely to be a donor-to-acceptor pair transition. For undoped samples, the intensity of this peak relative to that of the donor-to-band transition decreased as the doping density decreased and was negligible for samples with residual doping less than 2×1015cm−3. A broad acceptor-to-donor pair transition PL peak was observed for Zn-doped samples.