Molecular beam epitaxial growth and photoluminescence of near-ideal GaAs-Al<i>x</i>Ga1−<i>x</i>As single quantum wells

Abstract

Single quantum wells with ∼120-Å GaAs wells and Al0.3Ga0.7As or GaAs-Al0.3Ga0.7As superlattice barriers were grown by molecular beam epitaxy under conditions known to produce very high-purity material. Low-temperature photoluminescence measurements indicate that the dominant recombination transitions are associated with free and bound excitons involving both light and heavy holes. A forbidden transition, possibly E21h, is also observed. The transition associated with electron-heavy-hole free excitons is most intense and has a linewidth of 0.3 meV at 2 K. The linewidths observed for these samples, grown with As4 species at 630 °C, are the smallest for 120-Å single quantum wells and are close to theoretically calculated limits.