Production and evolution of A-centers in n-type Si1-xGex.

Autor: Sgourou, E. N., Andrianakis, A., Londos, C. A., Chroneos, A.
Předmět:
Zdroj: Journal of Applied Physics; Mar2013, Vol. 113 Issue 11, p113507, 5p, 6 Graphs
Abstrakt: The vacancy-oxygen pair (VO or A-center) in n-type Si1-xGex crystals (x = 0, 0.025, 0.055) has been studied using infrared (IR) spectroscopy. It is determined that the VO production is suppressed in the case of n-type Si1-xGex as compared to Si. It is observed that the annealing temperature of the VO defect in Si1-xGex is substantially lower as compared to Si. The decay of the VO (830 cm-1) band, in the course of 20 min isochronal anneals, shows two stages: The onset of the first stage is at ∼180 °C and the decrease of the VO signal is accompanied in the spectra by the increase of the intensity of two bands at ∼834 and 839 cm-1. These bands appear in the spectra immediately after irradiation and were previously correlated with (VO-Ge) structures. The onset of the second stage occurs at ∼250 °C were the 830 cm-1 band of VO and the above two bands of (VO-Ge) decrease together in the spectra accompanied by the simultaneous growth of the 885 cm-1 band of the VO2 defect. Interestingly, the percentage of the VO pairs that are converted to VO2 defects is larger in the Si1-xGex samples with intermediate Ge content (x = 0.025) as compared with Si (x = 0) and with the high Ge content samples (x = 0.055). The results are discussed in view of the association of VO pairs with Ge. [ABSTRACT FROM AUTHOR]
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