We perform high-resolution photocurrent (PC) spectroscopy to investigate resonantly the neutral exciton ground-state (X 0 ) in a single InAs/GaAs self-assembled quantum dot (QD) embedded in the intrinsic region of an n-i-Schottky photodiode based on a two-dimensional electron gas (2DEG), which was formed from a Si  -doped GaAs layer. Using such a device, a single-QD PC spectrum of X 0 is measured by sweeping the bias-dependent X 0 transition energy through that of a fixed narrow-bandwidth laser via the quantum-confined Stark effect (QCSE).By repeating such a measurement for a series of laser energies, a precise relationship between the X 0 transition energy and bias voltage is then obtained. Taking into account power broadening of the X 0 absorption peak, this allows for high-resolution measurements of the X 0 homogeneous linewidth and, hence, the electron tunnelling rate. The electron tunnelling rate is measured as a function of the vertical electric field and described accurately by a theoretical model, yielding information about the electron confinement energy and QD height. We demonstrate that our

We present bias-dependent micro-photoluminescence (μ-PL) spectroscopy of the neutral (X 0) and singly negatively-charged (X −) excitons in single InAs/GaAs self-assembled quantum dots (QDs) embedded in the intrinsic region of an n-i-Schottky diode based on a two-dimensional electron gas (2DEG), which was obtained from a Si δ-doped GaAs layer. Using such a device structure, we demonstrate bias-controlled single-electron charging of a single QD as the QD s-shell electron state is tuned below the Fermi level. This is verified experimentally by the sequential appearance of energetically-distinct PL emission lines from the two excitons and supported by theoretical calculations. In addition, it is shown both experimentally and theoretically that simultaneous PL emission from the X 0 and X − excitons within a particular bias range is the result of a long-lived charge-nonequilibrium state due to weak tunnel-coupling between the QDs and 2DEG in our device. Further, the ability to tune the exciton transition energies via the quantum-confined Stark effect is observed, offering insight into the carrier wave function distributions in the QD and the QD material structure. Finally, we propose a number of spintronic device concepts that may be made feasible as a result of this investigation into bias-controlled carrier tunneling between a self-assembled QD and a 2DEG.

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