1. Applied forward voltage
Hollow circles are holes, solid circles are free electrons, the p region is positively charged, and the n region is negatively charged. The current limiting resistor R is to limit the excessive current and protect it.
The forward current overcomes the depletion layer voltage to turn on the circuit.
2. Applied reverse voltage
When the reverse voltage is applied, there will be a drift movement of the minority carrier, and there will be a weak current. The current here is temperature sensitive.
3. Volt-ampere characteristic curve of PN junction
Its current equation:
I s is the reverse saturation current;
U t is the temperature equivalent, which converts the temperature into a voltage, which is 26mv at room temperature;
U is the voltage applied to the PN junction, at least several hundred mv;
the conduction voltage of the PN junction : Ge (germanium) tube: 0.2v~0.3v, Si (silicon) tube: 0.6v-0.7v;