TECHNIQUE FOR MEASUREMENT OF THE MINORITY-CARRIER MOBILITY WITH A BIPOLAR JUNCTION TRANSISTOR

A simple technique to measure the minority carrier mobility using a bi polar junction transistor is demonstrated. By fixing the base-emitter voltage, the carrier injection into the base is constant. The collecto r current is then monitored as a function of a magnetic field applied perpendicular to the current transport across the base. The magnetic f ield leads to an increase in base transit time and a corresponding dec rease in collector current. From the resulting fractional change in;co llector current, the minority carrier mobility in the base can be dete rmined. For narrow base transistors, quasiballistic transport across t he base must be taken into account when determining the bulk minority carrier mobility. (C) 1997 American Institute of Physics.