A diode is a two-terminal electronic component. There will be conductance in one direction and great resistance in other direction. The diode is made with the semiconductor material and the p-n junction will be connected to two electrical terminals. If you notice a vacuum diode, there will be two electrodes. They are plate and cathode. The semiconductor-based diodes were developed in 1906 and they are made with mineral crystals such as galena. Even though most of the diodes are made with silicon, they are made with selenium and germanium as well.
Function of diode
The common function of the semiconductor diode is to allow the passage of current in one direction. It will block the passage of current in the other direction. You can understand that the diode will be similar to a check valve. This kind of behavior is called rectification. Hence, diodes are used in converting Alternating Current (AC) into Direct Current (DC). The diode can extract modulation from radio signals from receivers.
In addition to simple on and off applications, diodes can be used for complicated applications. The diode has nonlinear current-voltage characteristics. The semiconductor diode can conduct electricity at a certain threshold voltage. It will pass electricity in the forward direction only. There will be a voltage drop in the forward-biased diode will vary with the temperature and there will be little variation with the current. The condition can be applied in voltage referencing and in temperature sensors.
Types of semiconductor diodes
There are different types of semiconductor diodes. The characteristics of the diode will change based on geometric scaling, doping level and the selection of electrodes. Semiconductor diode can be used in a special circuit so that you can make the most of your investment.
Normal diodes are made up of doped silicon and in some cases, they are made with germanium as well. Various kinds of diodes include avalanche diodes, cat’s whisker (crystal) diodes, constant current diodes, tunnel diodes, gunn diodes and light-emitting diodes. There are laser diodes, thermal diodes, photodiodes and the gold-doped diodes as well. If you go for gold-doped diode, the gold will act as a recombination center and it results in quicker recombination of minority carriers. If there is higher forward voltage drop, the diode will operate at the signal frequency.
You should understand the fact that gold-doped diodes are faster than p-n diodes. There will be less reverse current leakage than Schottky diodes. A special type of diode has been designed which has forward voltage characteristics. The diode can be used in low voltage stabilization applications. If there is requirement of certain level of voltage without fail, you should deploy the most appropriate diodes in the circuit.
As you go for zener diodes, you will experience breakdown at a definite voltage and the diode can be used for precision voltage reference. The breakdown voltage of zener diodes will be less than 5 volts. You can use avalanche diodes if the breakdown voltage is more than 5 volts. You can connect diodes in series to achieve a different functionality.