Electron Mobility and Drag Effect in p-Type Silicon

The drift mobility of electrons in p-type silicon containing acceptor concentrations from 1.4×10 13 cm -3 to 5.8×10 15 cm -3 was measured by the time-of-flight technique. The experiments were carried out at temperatures from 77 K to 300 K by applying electric fields between 25 V/cm and 700 V/cm. In the ohmic region, a large reduction in mobility was observed below 150 K in low-resistivity samples. By applying Mclean and Paige's theory, it was found that this reduction is due to the drag effect by the majority holes. In the warm electron region, the mobility of electrons was found to be smaller than that for an intrinsic material. This is the first observation of the enhancement of the drag effect of the electric field.