A PN junction is formed on a single crystal wafer of N-type germanium or silicon by alloying with metals such as indium and aluminum.
A PN junction formed by selectively diffusing only a portion of P-type impurities on a semiconductor single crystal wafer (mainly N-type silicon single crystal wafer) and utilizing the shielding effect of the silicon wafer surface oxide film.
The basic principle is to use the formed Schottky barrier on the contact surface between metal (such as lead) and semiconductor (N-type silicon wafer) to block reverse voltage.
Most diodes can be used as limiters. There are also specialized limiting diodes such as protective instruments and high-frequency Zener diodes.
The low-power diode used for automatic frequency control (AFC) and tuning is called a varactor diode.
This is a crystal diode constructed by sandwiching an intrinsic semiconductor (or a semiconductor with low concentration impurities) between the P and N regions.
