Exciton properties and optical response inInxGa1−

Abstract

Exciton binding energies and optical response in quantum wells and in multiple quantum wells of GaAs/In Gay As/GaAs are computed by a variational envelope-function procedure using the four-band model and the simpler two-band model. The eKect of hydrostatic and uniaxial strain are considered from a virtual-crystal stress Hamiltonian. The physical parameters used for the alloy (In Gaz As) are obtained by interpolating the parameter values of pure materials (GaAs, InAs). We verify that band-oHset values in the range of 0.30 -0.45 give exciton states and optical response in good agreement with experiments. The light-hole exciton energy is also well reproduced by theory and results are very close to the continuum states of the well, its binding energy being due to the attraction of the electron, localized inside the well.

Optical properties of InAlGaAs quantum wells: Influence of segregation and band bowing

“…18 To account for Coulomb interactions a well-width dependent exciton binding energy was used for the InGaAs structures in S1 and S2. 19 Based on the binding energy for a heavy-hole exciton in an 8 nm InGaAs quantum well, the binding energies of the heavy-and light-hole excitons in S3 were taken as 7 and 8 meV. Since the contributions of the exciton binding energies to the transition energies calculated in the following are small, discrepancies of a few meV compared to the real values will not affect the results.…”

“…18 The energies of the electron and hole states were found by solving the Schrödinger equation, using an isotropic conduction band model and a six-band k• p model for the valence band. For unstrained In x Ga 1Ϫx As the following relation was used for the low temperature band gap in eV: 19 1.519Ϫ1.584xϩ0.475x 2 ͑4͒…”

Optical properties of Ga 1− x In x As/GaAs(001) quantum well superlattices: Exciton and polariton dispersion curves

“…[3,14]) from which those of the GaInAs alloy are obtained using interpolation schemes as reported in Refs. [3,15].…”

“…[3,16]. For wavevector K varying in the first BZ, every exciton state defines a band of energy and the computed dispersion curves of the SLQW are obtained as shown in Fig.…”

“…The strain shifts conduction and valence band levels and completely removes the degeneracy at the Γ point of the p-like valence band states already split by the spin-orbit interaction [1][2][3][4]. Moreover, under biaxial strain the valence band masses become anisotropic (cylindrical symmetry), with different components m || (xy-plane) and m ⊥ (z-axis) parallel and perpendicular, respectively, to the longitudinal component of the strain [4].…”