EXPERIMENTAL-OBSERVATION OF A MINORITY ELECTRON-MOBILITY ENHANCEMENT IN DEGENERATELY DOPED P-TYPE GAAS

The variation of minority electron mobility with doping density in p+- GaAs has been measured with the zero-field time-of-flight technique. T he results from a series of nine GaAs films doped between 1 X 10(18) a nd 8 X 10(19) CM3 show the mobility decreasing from 1950 cm2 V-1 s-1 a t 1 X 10(18) cm-3 to 1370 cm2 V-1 s-1 at 9 X 10(18) cm-3. For the dopi ng range 9 X 10(18)-8 X 10(19) cm-3, the decreasing trend in mobility is reversed. The measured mobility of 3710 cm2 v-1 S-1 at 8 X 10(19) C M3 is about three times higher than the measured value at 9 X 10(18) C M-3 . These results confirm and extend recent transistor-based measure ments and are in accord with recent theoretical predictions that attri bute the increase in minority electron mobility in p+-GaAs to reductio ns in plasmon and carrier-carrier scattering at high hole densities.