Interband transitions of InAs/AlAs Short-Period superlattices grown by molecular beam epitaxy

In this work, we use spectroscopic ellipsometry (SE) to study the optical properties of (InAs)n/(AlAs)n short -period superlattices (SPS) with different period thicknesses for a wide wavelength range of 250 nm -1650 nm (about 0.75 eV - 5 eV). Additionally, the (InAs)2/(AlAs)2 samples grown at various temperatures (450, 475, 500, 525, 550 degrees C) were investigated. We extract the dielectric functions and adapt Adachi's model to obtain the interband transition energies of E0, E0 + Delta 0, E1, E1 +Delta 1 and E2. The quantum confinement effect and the strain effect lead to the decrease of E0, E0 + Delta 0, E1, E1 +Delta 1 with the increase of period thickness. It is also found that as the growth temperature rises from 450 degrees C, all the transition energies decrease as a result of the increase in the amplitude of lateral composition modulation and the relaxation of the compressive strain in InAs layers.

Automated summary

In this study, spectroscopic ellipsometry (SE) was used to investigate the optical properties of (InAs)n/(AlAs)n short-period superlattices (SPS) with different period thicknesses in a wide wavelength range. Additionally, (InAs)2/(AlAs)2 samples grown at different temperatures were also examined. The dielectric functions were extracted and Adachi's model was adapted to determine the interband transition energies. The results showed that the quantum confinement effect and strain effect led to a decrease in the transition energies with increasing period thickness. Moreover, as the growth temperature increased, all the transition energies decreased due to the enhanced lateral composition modulation and relaxation of compressive strain in InAs layers.