What is a germanium diode, its basic structure, performance parameters, working principle, application examples, differences and development history between germanium and silicon diodes 2

3、 Working principle:

The working principle of germanium diodes is similar to that of other diodes. When a forward voltage is applied to the PN junction of a germanium diode, due to the special structure of the PN junction, electrons diffuse from the N-type region to the P-type region, while holes diffuse from the P-type region to the N-type region. This diffusion phenomenon leads to the formation of a depletion layer near the PN junction, where there are almost no freely moving charge carriers. When the forward voltage reaches a certain value, the depletion layer disappears and current begins to flow through the diode, which conducts. When a reverse voltage is applied to the PN junction of a germanium diode, the depletion layer widens, making it almost impossible for current to pass through and the diode turns off.

4、 Application example:

Germanium diodes were widely used in electronic devices in the early days due to their low bandgap and high carrier mobility. Here are several application examples of germanium diodes:

1. RF detector: Germanium diodes can be used as detectors for RF signals, converting them into DC signals.

2. Temperature sensor: Due to the fact that the resistance of germanium diodes varies with temperature, they can be used as temperature sensors.

3. Voltage reference source: Due to the relatively stable forward voltage drop of germanium diodes, it can be used as a voltage reference source.

4. Pulse modulator: Germanium diodes can be used as pulse modulators to convert continuous signals into pulse signals.