Temperature dependence of the direct band gap energy and donor–acceptor transition energies in Be-doped GaAsSb lattice matched to InP

Abstract

The direct band energy (Eg) and donor–acceptor (D,A) transition energies are mapped as a function of temperature for Be-doped GaAsSb lattice matched to InP. Photoluminescence (PL) measurements over the temperature range 2 K≤T≤300 K yield two emission peaks, one of lower intensity and one of higher intensity. The lower intensity peak is believed to be Be related, while the higher intensity peak is from residual impurities. The emission energies of both PL peaks increase linearly with respect to the logarithm of excitation intensity, indicating the peaks are (D,A) transitions. Measurement of Eg was achieved using optical absorption spectroscopy over the range 14 K≤T≤300 K. A least squares fit of the absorption data using the Varshni equation produces a closed form expression for Eg(T) with coefficients α=13.5×10−4 eV/K, and β=135 K.

Optical properties of InAlAs/GaAsSb heterostructures grown by metalorganic vapor phase epitaxy

“…15 However, in Ref. 15 the peak shift at 10 K is less than 4 meV over 2 decades of laser intensity while our observed peak shift is ϳ16 meV over 1 decade with ␤ ϭ8.3 meV. In fact, this peak shift is greater than the maximum possible total shift of one-half the ionization energy of the shallower impurity.…”

“…Such donor-acceptor transitions have been observed in 3-m-thick, Be-doped GaAsSb. 15 However, in Ref. 15 the peak shift at 10 K is less than 4 meV over 2 decades of laser intensity while our observed peak shift is ϳ16 meV over 1 decade with ␤ ϭ8.3 meV.…”

Quasi-donor-acceptor pair transitions in GaAsSb and AlGaAsSb on InP

“…20 PL spectra of undoped GaAsSb layers, lattice matched to InP, show a dominant transition between 780 and 790 meV, 20 which is generally associated with a nonexcitonic residual impurity. 21 Transition energies shift by Ϸ6 meV toward higher energies, when the excitation intensity is varied from ϳ3 to 300 mW/ cm 2 ͑3 meV/ decade͒. 20 A lower transition is also observed at 30 meV, below the dominant peak in these alloys.…”

Optical Properties

“…Optical absorption measurements were undertaken on GaAs x Sb 1Àx by several authors [136][137][138]. The measured data were used to determine E 0 [136] and its temperature dependence [137,138].…”