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Optical absorption in highly strained Ge/SiGe quantum wells : the role of Γ→Δ scattering
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Lever, L., Ikonić, Z., Valavanis, A., Kelsall, Robert W., Myronov, Maksym, Leadley, D. R. (David R.), Hu, Y., Owens, N., Gardes, F. Y. and Reed, G. T. (2012) Optical absorption in highly strained Ge/SiGe quantum wells : the role of Γ→Δ scattering. Journal of Applied Physics, Volume 112 (Number 12). Article number 123105. doi:10.1063/1.4768935 ISSN 0021-8979.
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Official URL: http://dx.doi.org/10.1063/1.4768935
Abstract
We report the observation of the quantum-confined Stark effect in Ge/SiGe multiple quantum well heterostructures grown on Si0.22Ge0.78 virtual substrates. The large compressive strain in the Gequantum well layers caused by the lattice mismatch with the virtual substrate results in a blue shift of the direct absorption edge, as well as a reduction in the Γ-valley scattering lifetime because of strain-induced splittings of the conduction band valleys. We investigate theoretically the Γ-valley carrier lifetimes by evaluating the Γ→L and Γ→Δscattering rates in strained Ge/SiGe semiconductor heterostructures. These scattering rates are used to determine the lifetime broadening of excitonic peaks and the indirect absorption in simulated absorption spectra, which are compared with measured absorption spectra for quantum well structures with systematically varied dimensions. We find that Γ→Δscattering is significant in compressively strained Gequantum wells and that the Γ-valley electron lifetime is less than 50 fs in the highly strained structures reported here, where Γ→Δscattering accounted for approximately half of the total scattering rate.
Item Type: | Journal Article | ||||
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||
Journal or Publication Title: | Journal of Applied Physics | ||||
Publisher: | American Institute of Physics | ||||
ISSN: | 0021-8979 | ||||
Official Date: | 2012 | ||||
Dates: |
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Volume: | Volume 112 | ||||
Number: | Number 12 | ||||
Page Range: | Article number 123105 | ||||
DOI: | 10.1063/1.4768935 | ||||
Status: | Peer Reviewed | ||||
Publication Status: | Published | ||||
Access rights to Published version: | Restricted or Subscription Access |
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