SHUBNIKOV-DEHAAS OSCILLATIONS UNDER HOT-ELECTRON CONDITIONS IN SI SI1-XGEX HETEROSTRUCTURES/

The energy-loss rate of hot carriers in several modulation-doped Si/Si 1-xGex heterostructures has been studied. The Ohmic properties of the Si/Si1-xGex samples, which were grown by ultrahigh-vacuum chemical-vap or deposition, were studied by Hall effect, conductivity, Shubnikov-de Haas, and quantum Hall effect measurements. For the samples with mobi lities ranging from 1.3 X 10(4) to 1.3 X 10(5) cm2/Vs at T almost-equa l-to 2 K the ratio of the transport time to the single-particle scatte ring time increases from 2.4 to 7.7. This result clearly indicates the change from dominant short-range to rather long-range scattering mech anisms in the higher quality Si/Si1-xGex heterostructures. The depende nce of the energy-loss rate (P(E)) on electron temperature (T(e)) was obtained from the damping of the Shubnikov-de Haas oscillations with a pplied electric field up to 5 V/cm. In the electron temperature range from 1.6 to 7 K, the functional dependence of P(E) does not change whe n the mobility of the samples is varied by a factor of 10, and thus P( E)(T(e)) is unaffected by the nature of the elastic-scattering mechani sms within these limits. In this electron temperature range the domina nt energy-loss mechanism is due to acoustic-phonon scattering via defo rmation-potential coupling. For a deformation-potential coupling const ant of 9 eV, taking static screening into account, a quantitative agre ement between experimental and calculated values of the energy-loss ra te is obtained without any fit parameter.