Effects of Different Mobility of Electrons and Holes in Chains With Different Types of Conductivity

The different mobility of electrons and holes determines the performance characteristics of electronic devices built from complex materials. The analysis of physical phenomena in bipolar transistors is carried out. A switching circuit with a common emitter was chosen, which allows to study the currents and voltages of the base and collector. It is shown that the characteristics of a bipolar transistor are significantly influenced by the metal-semiconductor contact potential differences at its junction with conductors in a real circuit. The erroneous description of transistors with the hypothesis of feedback of collector and base voltages is revealed. The increase in the input voltage of the base-emitter (modulo) when the collector potential is applied and the current value is maintained is caused: in the npn transistor by a drop in the average energy of electrons coming to the base contact, and in the pnp transistor by the same drop in the average energy of electrons that enter the emitter from the collector. The material of the article is aimed at students studying electronics and engineer researchers working in the semiconductor industry. The adopted concept, together with the constructive solution of the semiconductor device, the properties of the metals used to actually connect the transistors.