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Photocurrent Spectroscopy of InAs/GaAs Self-Assembled Quantum Dots: Observation of a Permanent Dipole Moment

Published online by Cambridge University Press:  10 February 2011

P.W. Fry ,
I.E. Itskevich ,
D.J. Mowbray ,
M.S. Skolnick ,
J.A. Barker ,
E.P. O'Reilly ,
L.R. Wilson ,
I.A. Larkin ,
P.A. Maksym  and
M. Hopkinson
...Show all authors
P.W. Fry
Affiliation:
Department of Physics, University of Sheffield, Sheffield S3 7RH, UK
I.E. Itskevich
Affiliation:
Department of Physics, University of Sheffield, Sheffield S3 7RH, UK Institute for Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow district 142432, Russia
D.J. Mowbray
Affiliation:
Department of Physics, University of Sheffield, Sheffield S3 7RH, UK
M.S. Skolnick
Affiliation:
Department of Physics, University of Sheffield, Sheffield S3 7RH, UK
J.A. Barker
Affiliation:
Department of Physics, University of Surrey, Guildford GU2 5XH, UK
E.P. O'Reilly
Affiliation:
Department of Physics, University of Surrey, Guildford GU2 5XH, UK
L.R. Wilson
Affiliation:
Department of Physics, University of Sheffield, Sheffield S3 7RH, UK
I.A. Larkin
Affiliation:
Department of Physics, University of Sheffield, Sheffield S3 7RH, UK
P.A. Maksym
Affiliation:
Department of Physics, University of Leicester, Leicester LEI 7RH, UK
M. Hopkinson
Affiliation:
Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 3JD, UK
M. Al-Khafaji
Affiliation:
Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 3JD, UK
J.P.R. David
Affiliation:
Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 3JD, UK
A.G. Cullis
Affiliation:
Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 3JD, UK
G. Hill
Affiliation:
Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 3JD, UK
J.C. Clark
Affiliation:
Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 3JD, UK
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Abstract

Photocurrent spectroscopy of InAs/GaAs self-assembled quantum dots, studied as a function of applied electric field, is used to probe the nature of the confined electronic states. A field asymmetry of the quantum confined Stark effect is observed, consistent with the dots possessing a permanent dipole moment. The sign of this dipole indicates that for zero field the hole wavefunction lies above that of the electron, in disagreement with the predictions of all recent calculations. Comparison with a theoretical model demonstrates that the experimentally determined alignment of the electron and hole can only be explained if the dots contain a nonzero and non-uniform Ga content. The role of two different carrier escape mechanisms, tunneling and thermal excitation, is studied.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 571: Symposium W – Semiconductor Quantum Dots , 1999 , 147
Copyright
Copyright © Materials Research Society 2000

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References

REFERENCES

1. Bimberg, D., Grundmann, M. and Ledentsov, N. N., Quantum Dot Heterostructures (Wiley, 1998).Google Scholar
2. Grundmann, M., Stier, O. and Bimberg, D., Phys. Rev. B. 52, 11969 (1995).10.1103/PhysRevB.52.11969Google Scholar
3. Cusack, M., Briddon, P. R. and Jaros, M., Phys. Rev. B. 54, R2300 (1996).10.1103/PhysRevB.54.R2300Google Scholar
4. Pryor, C., Phys. Rev. B. 57, 7190 (1998).10.1103/PhysRevB.57.7190Google Scholar
5. Kim, J., Wang, L.-W. and Zunger, A., Phys. Rev. B. 57, R9408 (1998).10.1103/PhysRevB.57.R9408Google Scholar
6. Heitz, R. et al. Appl. Phys. Left. 68, 361 (1996); M. J.Steer, et al, Phys. Rev. B. 54, 17738 (1996).10.1063/1.116716Google Scholar
7. Warburton, R. J., Durr, C. S., Karrai, K., Kotthaus, J. P., Medeiros-Ribeiro, G. and Petroff, P. M., Phys. Rev. Lett. 79, 5282 (1997).10.1103/PhysRevLett.79.5282Google Scholar
8. Grundmann, M. et al. , Phys. Rev. Lett. 74, 4043 (1995).10.1103/PhysRevLett.74.4043Google Scholar
9. Miller, D. A. B., Chemla, D. S., Damen, T. C., Gossard, A. C., Wiegmann, W., Wood, T. H. and Burrus, C. A., Phys. Rev. B 32, 1043 (1985).10.1103/PhysRevB.32.1043Google Scholar
10. A small shift of 7 meV to higher energy has been applied to the results of sample B, in order to obtain a continuous variation of the peak positions between positive and negative electric fields. Samples A and B were grown consecutively in order to obtain the minimum possible run-to-run variation in dot parameters between samples. The observed energy difference of 7 meV corresponds to only a -2.5% variation in dot base size.Google Scholar
11. Raymond, S., Reynolds, J. P., Merz, J. L., Fafard, S., Feng, Y. and Charbonneau, S., Phys. Rev. B 58, R13415 (1998).10.1103/PhysRevB.58.R13415Google Scholar
12. Andreev, A. D., Downes, J. R., Faux, D. A. and O'Reilly, E. P., J. Appl. Phys. (unpublished).Google Scholar
13. Krijn, M. P. M. C, Semicond. Sci. Technol. 6, 27 (1991).10.1088/0268-1242/6/1/005Google Scholar
14. Joyce, P.B., Krzyzewski, T.J., Bell, G. R., Joyce, B.A. and Jones, T.S., Phys. Rev. B 58, R15981 (1998).10.1103/PhysRevB.58.R15981Google Scholar
15. Grandjean, N., Massies, J. and Tottereau, O., Phys. Rev. B. 55, R10189 (1997).10.1103/PhysRevB.55.R10189Google Scholar
16. Bransden, B.H. and Joachain, C.J., Introduction to Quantum Mechanics (Longman 1989).Google Scholar
17. The total offset (400 meV) between the QD ground state transition and the GaAs band gap is assumed to be split 50:50 between the valence and conduction bands and the GaAs electron effective mass is used.Google Scholar
18. Buckle, P. D., Dawson, P., Hall, S. A., Steer, M. J., Mowbray, D. J., Skolnick, M. S. and Hopkinson, M., Submitted to J. Appl. Phys.Google Scholar