STRAIN AND QUANTUM CONFINEMENT EFFECTS IN ENERGY-GAP REDUCTION OF QUANTUM-WELLS

We have discussed the energy-gap reduction due to exchange interaction and Coulomb correlation for quasi-two-dimensional InxGa1-xAs/InGaAsP quantum wells with variation of the well-width and the biaxial compres sive strain as a function of the sheet density. The exchange-correlati on self-energies have been calculated within the random-phase approxim ation, by solving a 4 x 4 Luttinger-Kohn Hamiltonian for the considera tion of the valence-band nonparabolicity of the strained layer. We hav e found that the energy-gap reduction by the many-body effects grows w ith an increase of the biaxial compressive strain and the quantum conf inement effect. At sheet density of n(s) = 1 x 10(12) and 1 x 10(13) c m(-2), our calculations show that for biaxial compressive strains of 0 .47 to 1.02% and for well-widths of 40 to 20 Angstrom the reduction ra tios of the band-gap energy are about 3.9 to 4.6% and 3.1 to 4.26%, re spectively.