Why silicon is used instead of germanium?
Why is silicon usually preferred to germanium in the manufacture of semiconductor devices? Silicon is abundant on the earth’s surface and therefore cheaper than germanium. The PIV (Peak Inverse Voltage) rating of silicon is much higher than germanium and therefore can withstand much higher temperatures than germanium.
What is the difference between silicon and germanium diodes?
A Silicon Diode is a semiconductor that has both positive and negative charge polarity and can allow an electrical current to flow in one direction whilst restricting another. Silicon Diodes have a forward voltage of approximately 0.7 volts whereas Germanium Diodes have a forward voltage of approximately 0.3 volts.
Why do we prefer silicon for transistor?
Silicon is used for electronic devices because it is an element with very special properties. One of it’s most important properties is that it is a semiconductor. This means that it conducts electricity under some conditions and acts as an insulator under others.
Why is Zener diode reverse biased?
It acts as a normal diode in forwarding bias. When the Zener diode is reverse biased the junction potential increases. As the breakdown voltage is high this will provide high voltage handling capacity. As the reverse voltage is increased, the reverse current increases drastically at a certain reverse voltage.
What is zener breakdown phenomena?
The phenomenon of the Zener breakdown occurs in the very thin depletion region. The thin depletion region has more numbers of free electrons. The reverse bias applies across the PN junction develops the electric field intensity across the depletion region. This process is known as the Zener breakdown.
What is tunneling in zener breakdown?
Tunneling occurs when the depletion region is too thin due to high doping concentration P and N region. You can call it abrupt junction. When the temperature is increased, the current will increase or breakdown voltage decreases. This is due to the higher energy of charge carriers which will cross the barrier easily.
What is the effect of Zener diode?
The Zener effect is a type of electrical breakdown that occurs in a reverse-biased PN junction when the electric field enables tunnelling of electrons from the valence to the conduction band of a semiconductor, leading to a large number of free minority carriers which suddenly increase the reverse current.
Why Zener diode do not damage after breakdown?
Zener effect incubates when on applying the bias voltage across the diode the valence band of p-region nearly aligns (precisely depends on temperature) with the conduction band of n-region. Here diode does not have any physical breakdown, and hence does not get damaged.
Why is Zener diode preferred?
For an AC/DC rectifier you use diodes unless you have a very specific need for a rectified current with a peculiar waveform that would be created by zener diodes. You can actually use a zener diode with a breakdown voltage higher than the peak value of the AC you’re rectifying, instead of using normal diodes.
Why is a Zener diode heavily doped?
The Zener diode, however, is heavily doped, as a result, they have a thin depletion region. Zener diode, under forward bias condition, conducts like a normal diode and if the applied voltage is higher than the reverse voltage then it conducts in the reverse bias condition too.
What is main cause of Zener breakdown?
The main cause of zener breakdown is high doping concentrations. For heavily doped junctions, when reverse voltage is increased, the electric field at junction increases (as more carriers are present now to create such a pull) which causes covalent bonds to break.
Can Zener be used as a rectifier?
Unlike the normal p-n junction diode, a Zener diode has a low peak inverse voltage. This is an undesirable property for the rectifier circuit. This is the reason why Zener diodes are not used for rectification purpose but are mostly used in applications that require voltage regulation.
Can we distinguish between Zener diode?
A Zener diode is made up of a PN junction but heavily doped compared to a normal diode. As a result, it can undergo breakdown without being damaged. And Due to this property only, Zener is used as a voltage regulator in electronic circuits. In fact, Zener diodes are never used for rectification purposes.