Near-surface GaAs/Ga0.7Al0.3As quantum wells: Interaction with the surface states

We report a study by ultra-high-vacuum photoluminescence of the interaction of surface and near-surface GaAs/${\mathrm{Ga}}_{0.7}$ ${\mathrm{Al}}_{0.3}$As quantum wells with the free surface. For surface-barrier thicknesses below 150 Å, strong redshifts (up to 40 meV) and intensity decreases (up to 1/1000) of the quantum-well peak are observed, revealing the coupling of the confined states with surface states located near the band edges. While demonstrating quantum wells to be promising surface probes, this observation opens a way to untangling confinement and interface effects on electron states in low-dimension systems such as clusters and one-dimensional–zero-dimensional nanostructures.