| Autor: |
Sheng, S.R., Rowell, N.L., McAlister, S.P. |
| Předmět: |
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| Zdroj: |
Applied Physics Letters; 10/6/2003, Vol. 83 Issue 14, p2790, 3p, 4 Graphs |
| Abstrakt: |
We report a study of photoluminescence (PL) and optical absorption in high-quality tensile-strained Si type-II multiple quantum wells (QWs) grown on bulk crystal SiGe substrates by using low-temperature ultrahigh-vacuum chemical vapor deposition. Detailed PL experiments, as a function of excitation density together with applied uniaxial stress, were performed to study the band alignment and to help elucidate the origin of the observed PL peaks. Spatially direct and indirect transitions of the Si QWs and an intense broad subgap PL were observed. With increasing excitation power, the PL lines of Si QWs shift to lower energies, whereas the broad PL shifts to higher energy. The applied [110] compressive stress results in a redshift of the substrate PL lines, as expected, but a blueshift of both the Si QW PL and the broad PL lines. The optical absorption data also show strong absorption in the near-infrared region where the broad PL was observed. Near the absorption edge (E[sub g]), the energy dependence obeys a square law rather than a square root law, suggesting that E[sub g] is associated with a quasi-direct transition. The E[sub g] value deduced according to the square law agrees well with the broad PL peak energy provided that temperature-dependent E[sub g], excitonic binding energy, and exciton localization energy, as well as quantum confinement are considered. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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