Analysis of strained InGaAs/InGaAsP single quantum wells using room temperature photoreflectance

Abstract

Room temperature photoreflectance (PR) has been performed on five nominally 90 Å wide undoped single quantum well (QW) structures in barriers, lattice matched to an InP substrate. The nominal QW Ga composition varies between x = 0.47 and x = 0.68, corresponding to tensile strains between zero and 1.47%, respectively. Room temperature photoluminescence measurements are also performed on the same position on the sample as the PR. Allowed and forbidden interband QW transition energies, given by least-squares fitting to the PR, are found to agree well with theoretical predictions based on an effective mass formalism, including excitonic binding energies and quantum-confined Stark effects. In achieving this agreement, values for the QW composition, thickness and band offset are determined by refining their nominal values. The conduction band offsets are found to range from 0.35 to 0.14 for tensile strains between zero and 1.40%. The energies of the ground state light- and heavy-hole QW transitions increase roughly linearly with tensile strain.