| Autor: |
O. A. Mironov, V.P. Gnezdilov, G. Braithwaite, P. J. Phillips, V.I. Khizhny, Evan H. C. Parker, Terry E. Whall |
| Rok vydání: |
1995 |
| Předmět: |
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| Zdroj: |
Journal of Crystal Growth. 157:382-385 |
| ISSN: |
0022-0248 |
| DOI: |
10.1016/0022-0248(95)00359-2 |
| Popis: |
In the present work the hybrid acoustic spectroscopy technique has been used to demonstrate the conversion of a high frequency (HF) electric field into acoustic waves and to provide the first direct observation of the piezoelectric effect in the SiGe/Si strained layer system. The sample was a p-type modulation doped Si 0.88 Ge 0.12 /Si heterostructure containing a two-dimensional hole gas with carrier sheet density 2 X 10 11 cm -2 and a 4.2 K mobility of 10500 cm 2 V -1 s -1 . It was excited with a 225.7 MHz high frequency pulse of 1 μs duration and 0.5 W peak power. The amplitude of the output acoustic signal was about 110 dB below the electromagnetic input signal at 77 K. We believe that the observed electric field-acoustic conversion is associated with the non-centrosymmetric structure of the ordered unit cell of the strained SiGe alloy. Additionally we report on phonon Raman scattering at T = 300 K and hot hole Shubnikov-de Haas and zero magnetic field resistivity behaviour in the same heterostructures in the temperature range of 0.35 to 1.4 K. A broad band near 255 cm -1 and a peak near 435 cm -1 have been attributed to a particular Si-Ge ordering within the alloy layer. The energy relaxation of the carriers has been measured and is found to be dominated by a weakly screened piezoelectric coupled acoustic-phonon mechanism, thereby providing further evidence of ordering in the SiGe alloy. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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