Experimental verification of the physics and structure of the bipolar junction transistor

We present an electrical characterization of discrete Bipolar Junction Transistor (BJT) devices with nonuniform doped emitter and base zones. The measurement of the I–V and C–V characteristics of the emitter–base and the collector–base junctions and the common emitter current gain allows to determine relevant parameters of the device. These are the built-in voltage of both junctions, the impurity gradient profiles, the electrical area of both junctions, the base and the emitter Gummel numbers, and the collector doping. The whole experiment can be conducted in a laboratory session of 3–4-hour length and it is specifically addressed to students taking lectures in semiconductor device physics. The results obtained give a deep insight into both the physical structure and the physical processes involved in the transistor behavior.