Sb Quantum Research Articles

Normal incidence infrared photoabsorption in p-type GaSb/GaxAl1−xSb quantum wells

Absorption of infrared radiation at normal incidence from intervalence-subband transitions is investigated in p-type GaSb/Ga1−xAlxSb quantum wells. Normal incidence absorption is allowed in conventional p-type quantum wells due to the favorable properties of the p-like valence-band Bloch states and the heavy- and light-hole mixing. By using GaSb as the quantum-well material, which has the smallest heavy-hole effective mass of the commonly used III-V semiconductors, absorption can be further enhanced. We find that normal incidence absorption of 3000–6000 cm−1 can be easily achieved in these proposed quantum wells with well widths of 55–90 Å for the wavelength range of 8–12 μm and typical sheet doping concentrations of 1012 cm−2. This absorption strength is comparable to that in the intrinsic Hg1−xCdxTe detector. Strong absorption of normally incident radiation makes this structure a good candidate for infrared photodetection.

Optical properties of GaSb/Ga 0.69Al 0.31Sb single quantum wells grown by molecular beam epitaxy

Molecular beam epitaxial GaSb/Ga 0.69Al 0.31Sb quantum well structures were characterized by electrorelfectance and transmission electron microscopy. The optical properties analysed are in good agreement with the predictions of a simple model of confined layer states.

Far-infrared absorption spectra measured in InAs/Al0.36Ga0.64Sb quantum wells

Far-infrared absorption spectra have been measured for molecular beam epitaxial InAs/Al0.36Ga0.64Sb multiquantum wells by Fourier transform infrared spectroscopy using light incident normal to the layers. The special band lineup for this heterostructure system causes an overlap of the electron and hole states. The measured absorption peak varies in the wavelength range of 5–10 μm in the temperature range of 100–300 K.

Carrier densities in InAs–Ga(Al)Sb(As) quantum wells

With the aim to study the influence of substitutional species on the band schemes and charge transfers in type-II heterostructures, the InAs–GaSb based quantum well structures have been prepared by molecular-beam epitaxy with a replacement of GaSb by GaSbAs and GaAlSb. Galvanomagnetic measurements show a similar behavior of decreasing hole density with increasing alloy composition in both cases, suggesting a transfer process insensitive to the cation–anion nature of the alloying element. That the high electron mobility also decreases with the composition is primarily governed by the degree of lattice mismatch.