Solid State Electronic Devices, 7th Edition

4.2 Luminescence

When electron–​hole pairs are generated in a semiconductor, or when carriers are excited into higher impurity levels from which they fall to their equilibrium states, light can be given off by the material. Many of the semiconductors are well suited for light emission, particularly the compound semiconductors with direct band gaps. The general property of light emission is called luminescence.² This overall category can be subdivided according to the excitation mechanism: If carriers are excited by photon absorption, the radiation resulting from the recombination of the excited carriers is called photoluminescence; if the excited carriers are created by high-​energy electron bombardment of the material, the mechanism is called ...