Analysis of GaAsGaSbGaAs structures under optical excitation considering surface states as an electron reservoir

Hong Wen Hsieh*, Shun-Tung Yen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

We present a self-consistent model for the analysis of the carrier distribution, the band profile, and the transition energy of type-II aligned GaAsGaSbGaAs structures under optical excitation. The model considers the surface states as an electron reservoir, associated with pinning of the conduction band Fermi level at the midgap. In our model, the optical generated holes in the GaSb quantum well causes a potential well on one side of the GaSb layer, which can efficiently accommodate the optically generated electrons. Accordingly, we derive a relation connecting the excitation power to the carrier density. Using the relation and the effective triangular potential approximation, we obtain a simple formula for the transition energy shift as a function of the excitation power, which follows the cube-root rule quite well. The calculation allows the determination of the band offset of a type-II heterointerface by comparison with data from photoluminescence measurement. The result suggests the unstrained valence band offset of GaSbGaAs to lie between 0.5 and 0.55 eV. We also present a simplified model for analyzing the electronic and optical properties of type-II heterostructures without the need of a self-consistent calculation.

Original languageEnglish
Article number103515
JournalJournal of Applied Physics
Volume105
Issue number10
DOIs
StatePublished - 11 May 2009

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