What is field ionization in Zener diode?
What is field ionization in Zener diode?
The Zener effect was first proposed by Dr. Clarence Zener in 1934 from whom it gains its name. Impact ionisation: Impact ionisation is very different to Zener breakdown and it occurs when a high electric field is present in a semiconductor. Electrons are strongly attracted and move towards the positive potential.
What is the basic principle of Zener diode?
A Zener diode operates just like a normal diode when it is forward-biased. However, a small leakage current flows through the diode when connected in reverse biased mode. As the reverse voltage increases to the predetermined breakdown voltage (Vz), current starts flowing through the diode.
What are the two types of breakdown in Zener diode?
A zener diode has two distinctly different breakdown mechanisms: zener breakdown and avalanche breakdown. The zener breakdown voltage decreases as the temperature increases, creating a negative temperature coefficient (TC).
Why is the high electric field produced in Zener diode?
A Zener diode is fabricated by heavily doping both p and n sides of the junction. Because of heavy doping, a very thin (<10−6 m) depletion region is formed between the p and n sides, and hence, the electric field of the junction is extremely high (~5 × 106 V/m) even for a small reverse bias voltage of about 5V.
What is breakdown voltage in Zener diode?
Breakdown voltage for commonly available Zener diodes can vary widely from 1.2 V to 200 V. For diodes that are lightly doped the breakdown is dominated by the avalanche effect rather than the Zener effect. Consequently, the breakdown voltage is higher (over 5.6 V) for these devices.
What is VI characteristics of Zener diode?
V-I characteristics of Zener diode initially a small reverse saturation current Io flows across the diode. As the reverse voltage is increased, at a certain value of reverse voltage, the junction will be breakdown and drastically a large reverse current flow through the device. This breakdown is called Zener breakdown.
What is difference between reverse breakdown and avalanche breakdown?
Zener breakdown occurs because of the high electric field. The avalanche breakdown occurs because of the collision of free electrons with atoms….Zener Breakdown vs Avalanche Breakdown.
| Zener Breakdown | Avalanche Breakdown |
|---|---|
| It occurs in diodes that are highly doped. | It occurs in diodes that are lightly doped. |
How many types of breakdown are there?
Hint: There are two types of breakdowns in p-n junctions. Avalanche breakdown occurs due to the rapid collision of electrons with other atoms. Zener breakdown occurs because of the high electric field. Zener breakdown is the controlled version of Avalanche breakdown in a modified p-n junction.
Why depletion region is thin in Zener diode?
The p-n junction of the Zener diode is heavily doped to get a narrow depletion region. The narrow depletion region allows the ions to easily gain energy from the external source. In the reverse bias, the junction potential of the Zener diode is increased. It results in an increased current through the Zener diode.
How is the breakdown region set during the manufacturing of the Zener diode?
The breakdown voltage is determined by the resistivity of the diode. This is determined by the doping technique used during the manufacturing. The breakdown voltage is usually rated at 1 to 20% tolerance. The ability of a zener diode to dissipate power decreases as the temperature increases.
