Berlin 2005 – scientific programme

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HL: Halbleiterphysik

HL 45: Quantenpunkte und -dr
ähte: Transporteigenschaften II

HL 45.9: Talk

Monday, March 7, 2005, 17:00–17:15, TU P-N202

Determination of the electron confinement in self-organized 1.3 µm InGaAs/GaAs quantum dots by capacitance-voltage measurements — •Marcus Gonschorek, Heidemarie Schmidt, and Marius Grundmann — Universität Leipzig, Fakultät für Physik and Geowissenschaften, 04103 Leipzig, Germany

Using capacitance-voltage (CV) measurements we observe that due to electrons confined in InGaAs quantum dots the space charge behaviour of the n-GaAs-Schottky host diode is modified by additional plateau-like structures. We solved self-consistently the one-dimensional Poisson and drift-diffusion equation as a function of the voltage applied to the Schottky contact where the zero-dimensional density of the electron quantum dot states is modelled by Gaussian broadened lines. By comparing experimental and theoretical CV data obtained for differently doped n-GaAs Schottky diodes (1× 10¹⁶ −5× 10¹⁶ cm⁻³) where identical layers of self-organized InGaAs quantum dots are incorporated, we show that the growth-related doping profile has a significant effect on the CV data. In order to determine the electron confinement in self-organized 1.3 µm InGaAs quantum dots, we carefully consider the temperature dependence of the Schottky barrier energy and use the CV data measured in the temperature range from 4 up to 310 K to separate the growth-related doping effects[1] from the quantum dot related charging effects. [1] R. Wetzler, A. Wacker, E. Schöll, C.M.A. Kapteyn, R. Heitz, and D. Bimberg, Appl. Phys. Lett. 77, 1671 (2000).