Why germanium is not used in thyristor?
Ability to withstand at high temperature: silicon crystals have capability to withstand at higher temperature compare to germanium crystals . So if leakage current is produced in SCR it heats up the device then silicon crystals can withstand but not germanium crystals.
Why do we use silicon made thyristors instead of germanium?
At room temperature, Silicon crystal has fewer free electrons than Germanium crystal. This implies that silicon will have much smaller Collector cut off current than Germanium. The structure of Germanium crystals will be destroyed at higher temperature. However, Silicon crystals are not easily damaged by excess heat.
Why is SCR not made of germanium?
Thyristor is not made using germanium, because. its current handling capacity is less than silicon. it is a stable semiconductor. it has high leakage current.
Why silicon is usually preferred over germanium for fabrication semiconductor devices?
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.
Which is better silicon or Germanium?
The structure of Germanium crystals will be destroyed at higher temperature. However, Silicon crystals are not easily damaged by excess heat. Peak Inverse Voltage ratings of Silicon diodes are greater than Germanium diodes. Si is less expensive due to the greater abundance of element.
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 the basic principle of Zener diode?
Zener diode is connected in reverse bias, so once the Zener voltage exceeds then the current flows through the diode but there is an unnoticeable voltage drop. Hence in this way the voltage is limited across the load. In this way, it is used as a voltage regulator.
What are the disadvantages of Zener diode?
Disadvantages of Zener diode:
- Zener diode cancels out voltage by applying an even larger voltage in the reverse direction wasting electricity in the process.
- A Zener diode has a relatively poor regulation ratio and is generally not as good as the transistor.
What is the drawback of zener as a voltage regulator?
It has low efficiency for heavy load currents. It is because if the load current is large, there will be considerable power loss in the series limiting resistance. The output voltage slightly changes due to zener impedance as Vout = VZ + IZ ZZ.
What is the drawback of zener as a voltage regulator How can this be overcome?
Zener diodes keep consuming a large amount of current while the load may just need a very little amount of current. Disadvantages: Zener diodes cancel out voltages by applying even larger voltages in the reverse direction, wasting electricity in the process.
What causes a Zener diode to fail?
Most of the zener diodes fail due to the excess power dissipation across it. Each zener has a rated power dissipation by manufacturer when the power dissipation is greater than the rated then it fails. The power dissipation is the product of voltage drop across the zener and the current flow through it.
Which device is used as rectifier?
High-power rectifiers, such as those used in high-voltage direct current power transmission, employ silicon semiconductor devices of various types. These are thyristors or other controlled switching solid-state switches, which effectively function as diodes to pass current in only one direction.