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Proceedings Paper

Direct and indirect transitions in (GaAs)n/(AlAs)n superlattices with n=1-15
Author(s): Chihiro Hamaguchi; Takeshi Nakazawa; Toshimasa Matsuoka; Tomoki Ohya; Kenji Taniguchi; Hidetoshi Fujimoto; Kensuke Imanishi; Hiromu Kato; Yasutaka Watanabe
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Paper Abstract

Photoreflectance and photoluminescence measurements are carried out to clarify optical properties of (GaAs)/(AlAs) (n = 1-15) short-period superlattices, placing main interest in the crossover of direct-indirect transition and zone-folded weak transition. Photoreflectance spectra of (GaAs)/(A1As) with n < 10 exhibit a weak structure below the main (strong) structure. Photoluminescence peaks appear at the photon energies corresponding to the critical points of these weak and strong structures. Energy band calculations are performed by using the empirical tight-binding method. Calculations of momentum matrix elements between the top valence band and lowest three conduction bands at the I' point show an existence of weakly allowed direct transition below the strongly allowed direct transition edge in (GaAs)/(AlAs)with n < 5. These results strongly suggest that the observed weak structures in the photoreflectance arise from the weakly allowed direct transition, indicating that the conduction band reflects the nature of the zone-folding effect (Xi).

Paper Details

Date Published: 1 August 1990
PDF: 11 pages
Proc. SPIE 1286, Modulation Spectroscopy, (1 August 1990); doi: 10.1117/12.20856
Show Author Affiliations
Chihiro Hamaguchi, Osaka Univ. (Japan)
Takeshi Nakazawa, Osaka Univ. (United States)
Toshimasa Matsuoka, Osaka Univ. (Japan)
Tomoki Ohya, Osaka Univ. (Japan)
Kenji Taniguchi, Osaka Univ. (Japan)
Hidetoshi Fujimoto, Osaka Univ. (Japan)
Kensuke Imanishi, Osaka Univ. (Japan)
Hiromu Kato, Kwansei Gakuin Univ. (Japan)
Yasutaka Watanabe, Kwansei Gakuin Univ. (Japan)

Published in SPIE Proceedings Vol. 1286:
Modulation Spectroscopy
Fred H. Pollak; Manuel Cardona; David E. Aspnes, Editor(s)

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