Electrical conductivity of a semiconductor

This is a simple but neat experiment in which the n-type base of a unijunction transistor is investigated. It's resistance is measured as the temperature is varied from liquid nitrogen temperatures (-196 deg. C) to about 200 deg. C. The resistance of a semiconductor is an interplay of band structure and band gaps. As temperature changes majority and minority charge carries make transitions across bands. Students are expected to trace a temperature-dependent resistance graph and interpret it to correlate with the band structure. Two important physical quantities can be deduced from the data. First is the band gap and second is the temperature dependent mobility of charge carriers. The experiment 2.10 B is an update to 2.10 and uses the PhysLogger and PhysWatt family of instruments, that have been developed in-house.