High-frequency transport in p-type Si/Si_(0.87)Ge_(0.13) heterostructures studied with surface acoustic waves in the quantum Hall regime

摘要

The interaction of surface acoustic waves (SAWs) with p-type Si/Si_(0.87)Ge_(0.13) heterostructures has been studied for SAW frequencies of 30-300 MHz. For temperatures in the range 0.7< T< 1.6 K and magnetic fields up to 7 T, the SAW attenuation coefficient Γ and velocity change ΔV/V were found to oscillate with filling factor. Both the real σ_1 and imaginary σ_2 components of the high-frequency conductivity have been determined and compared with quasi-dc magnetoresistance measurements at temperatures down to 33 mK. By analyzing the ratio of σ_1 to σ_2, carrier localization can be followed as a function of temperature and magnetic field. At T=0.7 K, the variations of Γ, ΔV/V, and σ_1 with SAW intensity have been studied and can be explained by heating of the two-dimensional hole gas by the SAW electric field. Energy relaxation is found to be dominated by acoustic phonon deformation potential scattering with weak screening.