Electric-Field-Enhanced Extrinsic Photoluminescence in AlGaAs-GaAs Single-Quantum Wells

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Abstract
The low-temperature photoluminescence of a 5 nm Al x Ga1-x As-GaAs single-quantum well in an electric field normal to the quantum-well plane has been investigated. When only the GaAs quantum well is photoexcited, the luminescence exhibits a low-energy shift under both reverse and forward bias. This low-energy shift is accompanied by a line broadening. The experimental results are explained by two competing radiative recombination processes, i.e. intrinsic free-exciton recombination and recombination between n=1 electrons and neutral acceptor-like centers near the heterojunction interfeces. The application of an electric field displaces the hole distribution in the quentum well more strongly than the electron distribution and thus enhances the recombination process, including the acceptor-like centers near the hetero-junction interfaces.