The luminous principle of explosion-proof flashlight

The light-emitting principle of the explosion-proof flashlight The light-emitting diode of the explosion-proof flashlight is made of III-IV compounds, such as GaAs (gallium arsenide), GaP (gallium phosphide), GaAsP (gallium arsenide phosphorus) and other semiconductors. Knot. Therefore, it has the I-N characteristics of a general P-N junction, that is, forward conduction, reverse cutoff, and breakdown characteristics. In addition, under certain conditions, it also has light-emitting properties. Under the forward voltage, electrons are injected into the P zone from the N zone, and holes are injected into the N zone from the P zone. Part of the minority carriers (minority carriers) that enter the opposing area recombine with the majority carriers (many carriers) to emit light, as shown in the figure. Theory and practice have proved that the peak wavelength λ of light is related to the band gap Eg of the semiconductor material in the light-emitting region, that is, λ≈/Eg (mm) where the unit of Eg is electron volt (eV). If it can produce visible light (wavelength is between nm violet light ~ nm red light), the Eg of the semiconductor material should be between .～.eV. Light having a longer wavelength than red light is infrared light. It is not commonly used. The characteristics of the explosion-proof flashlight () allowable power consumption Pm allows the maximum value of the product of the positive DC voltage at both ends of the LED and the current flowing through it. If this value is exceeded, the LED will heat up and be damaged. () Maximum forward direct current IFm: The maximum forward direct current allowed to be added. Exceeding this value can damage the diode. () Maximum reverse voltage VRm: The maximum allowable reverse voltage. Above this value, the LED may be damaged by breakdown. () Working environment The ambient temperature range where topm light-emitting diodes can work normally. Below or above this temperature range, the light-emitting diode will not work normally and the efficiency will be greatly reduced. Assuming that light emission occurs in the P region, the injected electrons directly recombine with the valence band holes to emit light, or they are first captured by the luminescent center and then recombine with the holes to emit light. In addition to this luminescence recombination, some electrons are captured by the non-luminescence center (the center is near the middle of the conduction band and the dielectric band), and then recombine with the holes. The energy released each time is not large and can not form visible light. The greater the ratio of the luminous recombination to the non-luminous recombination, the higher the light quantum efficiency. Since the recombination emits light in the minority carrier diffusion region, the light is only generated within a few μm close to the PN junction surface.