Abstract
Photoreflectance (PR) spectra of AlxIn1-xSb-based heterostructures have been obtained by using a novel photomodulation Fourier-transform infrared (FTIR) spectroscopy method. The studied samples - bulk AlxIn1-xSb epilayers and InSb/AlxIn1-xSb heterostructures - were grown by molecular beam epitaxy on semi-insulating GaAs substrates via AlSb buffer layers. The critical-point energies E0 and E0+Δ0 of AlxIn1-xSb alloys of various direct-gap compositions were defined from the PR spectra features. It was found that the E0 values are greater than the observed AlxIn1-xSb photoluminescence peak energy, with the difference increasing with x. For the InSb/AlxIn1-xSb heterostructures, PR signals corresponding to Franz-Keldysh oscillations in the alloy barrier have been observed. Analysis of their period has allowed one to determine the intensity of the internal electric field in AlxIn1-xSb layers. This result enables evaluation of the surface Fermi level pinning, and elucidation of the effect of doping in such heterostructures.
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