Electronic Properties of InAs/GaAs Self-Assembled Quantum Dot Structures and Devices Studied by Photocurrent Spectroscopy
D.J. Mowbraya, P.W. Frya, M.S. Skolnicka, I.E. Itskevichb, L. Harrisa, A.D. Ashmorea, J.J. Finleya, L.R. Wilsona, K.L. Schumachera, J.A. Barkerc, E.P. O'Reillyc, M. Al-Khafajid, A.G. Cullisd, M. Hopkinsond, J.C. Clarkd and G. Hilld
a Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, U.K.
b School of Engineering, University of Hull, Cottingham Road, Hull HU6 7RX, U.K.
c Department of Physics, University of Surrey, Guildford GU2 5XH, U.K.
d Department of Electronic and Electrical Engineering, University of Sheffield
Sheffield S1 3JD, U.K.
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The power of photocurrent spectroscopy to study the electronic properties of InAs/GaAs self-assembled quantum dots is described. From comparison of results from different samples it is shown that photocurrent provides a direct means to measure absorption spectra of quantum dots. Studies in high electric field enable the electron-hole vertical alignment to be determined. Most surprisingly this is found to be opposite to that predicted by all recent predictions. Comparison with theory shows that this can only be explained if the dots contain significant amounts of gallium, and have a severely truncated shape. The nature of the ground and excited state transitions, carrier escape mechanisms from dots, in-plane wave function anisotropies and the modal gain of a quantum dot laser are determined.
DOI: 10.12693/APhysPolA.98.279
PACS numbers: 73.61.Ey, 78.66.Fd, 42.55.Px, 73.50.Pz