Current Multiplication in the Type-A Transistor

One of the basic phenomena exhibited by transistors is current multiplication. In transistors of the point-contact type (one of these has been called the type A), the mechanism giving rise to this effect has been somewhat uncertain. Four possible mechanisms of the current multiplication process in the type-A transistor are discussed. One of the mechanisms is based on trapping holes in the collector barrier of the semiconductor. By means of this trapping model, the effect of emitter current and temperature on the current multiplication is predicted. It is shown that these predictions are in reasonable accord with experiment. Furthermore, assuming this model to hold, the trap density and activation energy (produced by forming) may be evaluated.