The behavior of carriers in quantum wells in GaAs-A?xGa1 ?xAs superlattices under in-plane magnetic fields

Abstract

The effect of in-plane magnetic fields B up to 20 T on the carriers confined in symmetric (SQW) and asymmetric (AQW) quantum wells in n-type GaAs-A𝓁xGa1 – xAs superlattices is investigated by a self-consistent numerical solution of the Poisson plus Schrödinger equations. Quantum-well widths Lw = 75 Å, 150 Å, 225 Å, and 300 Å and 2D electron densities Ns = 0, 2.5, 5.0, and 7.5 (1011 cm−2) are considered. The diamagnetic shift in the electron-hole recombination energy is shown to increase with increasing Lw and decreasing Ns. For Lw ⩾ 225 Å and Ns ⩾ 2.5 × 1011 cm−2 the energy dispersion ϵ1(k) of the first conduction subband in the SQW presents, at high fields, a double-minimum character so that the gap becomes indirect. For the AQWM the symmetry ϵ1(k) = ϵ1(-k) is broken, and the gap is also indirect. Recent photoluminescence measurements are discussed in relation to the present calculations.