Simply put, P-type and N-type semiconductors are made on both sides of an intrinsic semiconductor by different doping. The holes in the P-type semiconductor are the majority carriers, and the electrons in the N-type semiconductor are the majority carriers. 7a64e78988e69d8331333330363761 Due to the difference in concentration, these two carriers will spontaneously spread to the other region. Because holes are positively charged and electrons are negatively charged, the two carriers will recombine at the interface, thereby forming a space charge region on both sides of the interface, and the direction of the electric field from N to P, which is the PN node. The formation of this internal electric field hinders the diffusion motion of most carriers, so the scale of the PN node is determined at a certain temperature (see Figure 1).

When a forward voltage is applied to the PN section (P-type semiconductor is connected to the positive electrode of the power supply, and N-type semiconductor is connected to the negative electrode of the power supply), the external electric field interacts with the internal electric field. The overall effect is to weaken the internal electric field, so that holes and electrons can diffuse into the other area. Form a stable current. At this time, when the high-energy state electrons and holes recombine, excess energy is released in the form of light, thereby directly converting electrical energy into light energy (see Figure 2). Of course, a reverse voltage is applied to the PN section of the light-emitting diode (P-type semiconductor is connected to the negative electrode of the power supply, and N-type semiconductor is connected to the positive electrode of the power supply). Since the internal electric field is strengthened, the diffusion movement of most carriers is further prevented, and the circuit cannot be turned on. Can't shine.

It is worth noting that not all semiconductor materials can be used to make light-emitting diodes. At present, GaP (phosphorus crop), GaAsP (phosphorus arsenide crop), etc. are mostly used.