Quantum Confined Stark Effect of excitons localized at very thin InAs layers embedded in GaAs

InAs monolayers (1.0–1.7 ML) embedded in GaAs can effectively bind Frenkel-like excitons in the perpendicular direction and have efficient optical heavy hole hh–e and light hole lh–e transitions below the GaAs bandgap. Despite the fact that the theoretically predicted extension of the hh, lh, and e-wave function into the GaAs host material suggests a sizeable Quantum Confined Stark Effect (QCSE) for 1.0 and 1.7 ML InAs, up to now possible electro-absorption effects in the InAs-ML/GaAs system have not yet been experimentally investigated. Here we report the first experimental study of the QCSE in the InAs-ML/GaAs system by means of photocurrent (PC) measurements on Au/n-GaAs Schottky diodes containing single 1.0 or 1.7 ML InAs. For a field of 195 kV/cm the Stark shift in the 1.7 ML InAs QW amounts to 17 (hh–e) and 12 meV (lh–e).