Compensation effect and differential capacitance analysis of electronic energy band structure in relaxed InAs quantum dots

Jenn-Fang Chen, Ross C.C. Chen, C. H. Chiang, M. C. Hsieh, Y. C. Chang, Yung-Fu Chen

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2 Scopus citations

Abstract

The use of a differential capacitance technique for analyzing the effect of strain relaxation on the electronic energy band structure in relaxed InAs self-assembled quantum dots (QDs) is presented. Strain relaxation is shown to induce a deep defect state and compensate the ionized impurity in the bottom GaAs layer, leading to a double depletion width and a long emission time. An expression of capacitance at different frequency and voltage is derived for analyzing the experimental data. It has been shown that the relationship between the low-frequency and high-frequency capacitances can be well explained by a Schottky depletion model with a compensated concentration in the bottom GaAs layer. A simple expression is presented to account for the modulation of the free electrons in the top GaAs layer. This capacitance analysis shows a long low-energy tail for the electron ground state, suggesting not very uniform strain relaxation. The results of this study illustrate a carrier compensation effect of the defect state on the electronic energy band structure near the QDs.

Original languageEnglish
Article number063705
JournalJournal of Applied Physics
Volume108
Issue number6
DOIs
StatePublished - 15 Sep 2010

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