Various classifications of crystal diodes 1

1、 Classification based on construction

Semiconductor diodes mainly operate by relying on PN junctions. The point contact type and Schottky type, which are inseparable from the PN junction, are also included in the scope of general diodes. Including these two models, based on the characteristics of PN structure surface construction, crystal diodes are classified as follows:

1. Point contact diode

Point contact diodes are formed by pressing a metal needle onto a single crystal of germanium or silicon material and then using the current method. Therefore, its PN junction has a small electrostatic capacity and is suitable for high-frequency circuits. However, compared to surface junction diodes, point contact diodes have poor forward and reverse characteristics, and therefore cannot be used for high currents and rectification. Due to its simple structure, it is inexpensive. For general applications such as detection, rectification, modulation, mixing, and limiting of small signals, it is a widely used type.

2. Key type diode

A key type diode is formed by fusing or silver filaments onto a single crystal of germanium or silicon. Its characteristics are between point contact diodes and alloy diodes. Compared with point contact type, although the PN junction capacity of key type diodes has slightly increased, their forward characteristics are particularly excellent. Commonly used as a switch, sometimes also applied to detection and power rectification (not greater than 50mA). In key type diodes, diodes with fused gold wires are sometimes referred to as gold bond type, while diodes with fused silver wires are sometimes referred to as silver bond type.