Characteristics, testing methods, and parameters of crystal diodes 1

shown in Figure 1:

Figure 1. Voltage current characteristic curve of diode

1. Positive characteristics

When the forward voltage (P is positive and N is negative) at both ends of the diode is very small (germanium tube is less than 0.1 volts, silicon tube is less than 0.5 volts), the tube does not conduct and is in a "dead zone" state. When the forward voltage exceeds a certain value, the tube conducts, and the voltage slightly increases, causing a sharp increase in current (see curve segment I). The starting voltage of diodes made of different materials varies, with silicon tubes ranging from 0.5-7 volts and germanium tubes ranging from 0.1-0.3 volts.

2. Reverse characteristic

When a reverse voltage is applied across the diode, the reverse current is very small. As the reverse voltage gradually increases, the reverse current remains basically unchanged, and this current is called the reverse saturation current (see curve segment II). The reverse current of diodes made of different materials varies, with silicon tubes ranging from 1 microampere to several tens of microamperes and germanium tubes reaching up to several hundred microamperes. In addition, the reverse current is greatly affected by temperature changes, and the stability of germanium tubes is worse than that of silicon tubes.