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Other semiconductor phenomena.. Electronics

Other semiconductor phenomena

Light is generated by the passage of current through gallium phosphide diodes or gallium arsenide diodes diffused in the forward direction or the conduction direction. It is known that the junction area in gallium arsenide diodes contains a large percentage of electrons and positive carriers, and that photons are emitted only when electrons move from one energy level to a lower level. In this case, the diodes act as a semiconductor laser or light amplifier, in which photons travel through the junction area and play the role of a catalyst in renewing photons and emitting more of them, thus increasing the intensity of the resulting light (275).

Conversely, activating the diodes, or stimulating them with photons, also generates an electric current. In a diodes with a small current, one electron is generated for every photon (276). In the silicon photodiode, the voltage applied to the junction releases a larger amount of electrons due to the increased energy of the photons present. In the phototransistor, the emitter and base are photodiodes, and the transistor amplifies the base current and generates a larger current in the collector (276).

275 - The light-generating diode.

276 The photodiode and the phototransistor.