TEMPERATURE-DEPENDENCE OF MINORITY HOLE MOBILITY IN N-GAAS MEASURED WITH A NEW VARIABLE-TEMPERATURE TECHNIQUE()

The temperature-dependent mobility provides essential information for device design and serves as a sensitive probe of minority carrier scat tering physics. As examples, dominant scattering mechanisms are identi fied by characteristic temperature dependencies of mobility and for lo w temperature bipolar device optimization, accurate minority carrier m obility data are required. We report the first temperature (T) depende nt measurement of minority hole mobility in n+-GaAs. The minority carr ier mobility (mu) was measured with the zero-field time-of-flight tech nique. In this technique, minority carrier diffusivity (D), where De = mukT, is determined from the transient response of a specially design ed photodiode that is excited by a high-speed laser. We have extended the technique to permit continuously variable, T-dependent minority mo bility measurements. The unique cryostat design, including device moun ting, low-loss feedthroughs and temperature measurement scheme, is pre sented.