SHUBNIKOV-DEHAAS OSCILLATIONS AND NEGATIVE MAGNETORESISTANCE UNDER HOT-ELECTRON CONDITIONS IN SI SIGE HETEROSTRUCTURES/

The energy loss rate of two-dimensional hot electrons has been studied in modulation-doped Si/SiGe heterostructures grown by ultrahigh-vacuu m chemical vapour deposition using the damping of the amplitudes of Sh ubnikov-de Haas oscillations with applied electric field up to 2 V cm- 1. The samples investigated had a carrier concentration of 1 x 10(12) cm-2. The ohmic properties of the samples were studied by photo-Hall e ffect, conductivity and quantum Hall effect measurements. From compari son of the experimental data with calculations it is shown that the do minant energy loss mechanism is due to acoustic phonon emission via de formation potential coupling for electron temperatures between 1.8 and 7 K. In addition the electric field dependence of the negative magnet oresistance due to weak localization for electric fields up to 2.1 V c m-1 was investigated for a lattice temperature of 1.8 K. The data were analysed to yield the dephasing time tau(phi) as well as the elastic scattering time tau(e).