Infrared photoreflectance of InSb-based two-dimensional nanostructures
An IR photoreflectance (PR) study of two-dimensional nanoheterostructures based on InSb was performed by using Fourier-transform IR photomodulation spectroscopy. The studied structures, including InSb/Al𝑥In1−𝑥SbInSb/AlxIn1−xSb quantum wells (QWs) and type-II nanostructures with monolayer-thick InSb insertions within bulk InAs layers, were grown via molecular beam epitaxy on GaAs (001) and InAs (001) substrates, respectively. The PR spectra of the InSb/Al𝑥In1−𝑥SbInSb/AlxIn1−xSb heterostructures exhibited a series of signals from the QWs, including the spin-orbit split band, as well as the Al𝑥In1−𝑥SbAlxIn1−xSb layers, which enabled control of the barrier height and composition. A comparison of the experimental results with calculations made by the effective mass approximation technique was used to identify several optical transitions observed within the QWs, including those related to the excited states not visible in the photoluminescence spectra. For the InSb/InAs monolayer nanostructures, an analysis of the PR spectra features allowed for determination of their energy spectrum, internal electric field value, and localization energy of holes up to room temperature.