PACS 73.20; 75.50 Pp

Capacitance spectroscopy of InAs self-assembled quantum dots

P. M. Martin*, A. E. Belyaev**, L. Eaves, P. C. Main, F. W. Sheard, T. Ihn***, M. Henini

Department of Physics, University of Nottingham, Nottingham, NG7 2RD, UK
*Present address: Dept. of Electronic & Electrical Engineering, University of Sheffield, Sheffield, S1 3JD, UK
**On leave from Institute of Semiconductor Physics, NASU, Kyiv, 252028, Ukraine
***Present address: Solid State Physics Lab., ETH Hoenggerberg, CH-8093 Zurich, Switzerland

Abstract. Capacitance spectroscopy is used to study electronic properties of self-assembled InAs quantum dots. The capacitance-voltage, C(V), measurements in combination with the magneto-capacitance, C(B), results make it possible to investigate the electrostatic profile of a series of single-barrier n-i-n GaAs/AlAs/GaAs heterostructures incorporating a layer of self-assembled InAs quantum dots in the AlAs barrier. We find that the negative charge associated with electron filling of the dots is closely compensated by a positive charge in the AlAs barrier, which we ascribe to ionised defects or impurities, possibly in association with the quantum dots. It is shown the compensation degree considerably depends on the growth conditions.

Keywords: MBE growth, InAs quantum dots, capacitance spectroscopy.

Paper received 16.09.98; revised manuscript received 19.10.98; accepted for publication 28.10.98.

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