Explanation

The phenomenon that the electric conductivity of semiconductor changes under the action of electromagnetic radiation. Generally, it refers to the increase of electric conductivity caused by the increase of charge concentration of movable carriers under light. For intrinsic semiconductor, the valence band electrons absorb photons and transition to the conduction band, increasing both the number of conduction band electrons and the number of valence band holes. This increases the electric conductivity of the semiconductor, which is called intrinsic photoconductivity. For doped semiconductor, electrons can be excited from the donor bound state in the band gap to the conduction band to produce electronic conduction; It can also be that the valence band electrons excite the acceptor state in the forbidden band and increase the holes in the valence band to produce hole conduction. These two are collectively called impurity photoconductivity. In fact, there are three kinds of excitation processes, but one kind of excitation mechanism is mainly used for a semiconductor materials. The use of photoconductivity can be made into photoresistors, photoconductive diodes and phototransistors.

Classification