Crystal diode P-N junction and its unidirectional conductivity 1

As mentioned earlier, the conductivity of impurity semiconductors can be greatly improved, but its meaning is far from that. If a special process method is used on a single crystal wafer,diode different impurities are doped on both sides to form P-type or N-type semiconductors, respectively, the interface between the two semiconductors forms a P-N junction, as shown in the following figure. P-N junction is the foundation of various semiconductor devices. ① The formation of P-N junction. The P-type and N-type semiconductors in Figure 5-7 are commonly referred to as P and N regions.diode  Due to the presence of a large number of holes in the P region and a large number of free electrons in the N region, there is a difference in carrier concentration, resulting in diffusion motion. The diffusion motion first occurs at the interface, and the holes in the P region diffuse towards the N region. On one side of the P region near the interface, immovable negatively charged boron ions are left, forming a negative space charge region. At the same time, free electrons in the N region diffuse towards the P region, leaving immobile positively charged phosphorus ions near the interface on one side of the N region, forming a positive space charge region. This forms a space charge region on both sides of the interface between the P and N regions. This space charge region is the P-N junction.diode