Schottky Diodes

The Schottky diodes  are often called “4-layer diodes” because 2 layers of each type of semiconductor material is included in their construction. The result is a NPNP device. As with all other types of diodes, they are two-lead devices.

The Schottky family of diodes includes a PIN diode, this is sometimes referred to as the silicon hot-carrier diode. These are breakdown devices, means that their useful role is to become highly conductive in case when the reverse voltage across them exceeds the value of an inherent trigger voltage. Not like zener diodes, these diodes do not maintain their

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Zener Diodes

The Zener diodes are primarily used as voltage regulator devices. These devices are specific type diodes designed to be operated in the reverse breakdown region. Every zener diode has been manufactures for a specific reverse-breakdown voltage that`s called the zener voltage (VZ).

For understanding the operational aspects of zener diodes, refer to Figure

below. See the symbol being used to represent a zener diode. In this illustration, a 5.6-volt zener has been chosen. Also consider that we can apply a variable DC voltage to the +ve and -ve terminals of the circuit, that should be ranging from zero to 10 volts. Starting at 0 volt, as the voltage level is increased up to 5.6 volts, the zener diode behaves like any other reverse-biased diode. It completely blocks any significant current flow. And, that’s why it represents an almost infinite resistance; the whole applied voltage will be dropped across it. This all discussion holds true up to the point when the voltage we supplied exceeds the rated zener voltage (ZV) of the diode. When this avalanche voltage occurs, the zener diode will abruptly start to conduct current freely. Avalanche point is that pony at which this abrupt operational change happens.

The minimum amount of current flow through the zener diode which is required to keep it in an avalanche mode of operation is called the holding current. The voltage level across the zener diode does not decrease when the avalanche point is reached, but it does not increase by a very significant amount as the supplied circuit voltage is increased by a significant value. Hence, the voltage level across the zener diode is regulated, or held constant.

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