Effect in Coherently Strained B-Doped (001)SiGe/Si Heterostructures
V.I. Knizhny, O.A. Mironov, O.A. Makarovskii
Institute of Radiophysics and Electronics, National Academy of Sciences of Ukraine, 12, Acad. Proscura st., Kharkov, 310085, Ukraine

G. Braithwaite, N.L. Mattey, E.H.C. Parker and P.J. Phillips
Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
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We report on two methods which illustrate piezoelectric effects in the strained Si (100)Si1-x/Gex system. The non-contact sound excitation tech­nique has been used to reveal the conversion of a high-frequency electric field E into acoustic waves at 77 K which can also be modulated by a dc applied bias voltage (±30 V). The sample was an MBE grown modulation doped Si0.88Ge0.12/(001)Si structure with a carrier sheet density 2.0 × 1011 cm-2 and a 4.2 K mobility 10500 cm2 V-1 s-1. We deduce that the observed high-frequency electric field acoustic wave conversion is associated with a piezoelectric-like effect possibly due to ordering in the strained SiGe alloy or symmetry breaking effect near Si/SiGe interface. Further evidence is pro­vided by the existence of a piezoelectric phonon interaction in the hot hole energy relaxation mechanism determined from high electric field Shubnikov de Haas He3 low temperature measurements.
DOI: 10.12693/APhysPolA.88.779
PACS numbers: 73.50.Rb, 73.61.Cw, 73.50.Μx