Abstract
AbstractIn this paper, we study the electrical and optical properties of the InGaAs/InAlAs hetero-structure quantum wells, including strained effect, split-off bands, the effects of free-carrier screening and the doping effect. We have studied the change of the band structures and its consequences in different situations.The Luttinger-Kohn and Pikus-Bir model is used to study the valence band structures and the influences of the split-off (SO) bands and strained effects to the quantum well. At lower energy, the constant- energy surfaces are more deformed by the strained effect. The HH and LH bands are pushed upward by the SO band. The self-consistent Schrodinger and Poisson’s equation are solved by the finite different method to study the quantum wells. Under the applied electric field the potential profiles are tilted. The screening of free carriers affects can cause the flattening of the potential profile in the quantum well and also cause the energy shift of states near quasi-Fermi level. In the study of the inter-subband optical absorption of the n-type modulation-doped quantum well, the transition energies are found to increase as the electric-field increases. The transition energies decrease and the absorption coefficients increase as the doping concentration increases. The maximum absorption coefficients occur at the transition energy and the refractive indices also change dramatically near the transition energy.