Lookup NU author(s): Dr Jonathan Mar
This is the final published version of an article that has been published in its final definitive form by AIP Publishing LLC, 2011.
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We perform high-resolution photocurrent (PC) spectroscopy to investigate resonantly the neutral exciton ground-state (X0) 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 δ-doped GaAs layer. Using such a device, a single-QD PC spectrum of X0 is measured by sweeping the bias-dependent X0 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 X0 transition energy and bias voltage is then obtained. Taking into account power broadening of the X0 absorption peak, this allows for high-resolution measurements of the X0 homogeneous linewidth and, hence, the electron tunneling rate. The electron tunneling 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 devices can operate as 2DEG-based QD photovoltaic cells and conclude by proposing two optical spintronic devices that are now feasible.
Author(s): Mar JD, Xu XL, Baumberg JJ, Irvine AC, Stanley C, Williams DA
Publication type: Article
Publication status: Published
Journal: Journal of Applied Physics
Online publication date: 15/09/2011
Date deposited: 15/06/2020
ISSN (print): 0003-6951
ISSN (electronic): 1077-3118
Publisher: AIP Publishing LLC
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