What are the surface defects?
Surface defects are the boundaries, or planes, that separate a material into regions, each region having the same crystal structure but different orientations.
What are the types of line defect?
- Point defects (vacancies, interstitial defects, substitution defects)
- Line defect (screw dislocation, edge dislocation)
- surface defects (material surface, grain boundaries)
- Substitutional – one atom is replaced by as different type of atom.
- Interstitial – extra atom is inserted into the lattice structure at a.
What is the defect?
A defect is a physical, functional, or aesthetic attribute of a product or service that exhibits that the product or service failed to meet one of the desired specifications.
What is Frenkel defect?
The Frenkel defect (also known as the Frenkel pair/disorder) is a defect in the lattice crystal where an atom or ion occupies a normally vacant site other than its own. As a result the atom or ion leaves its own lattice site vacant.
What are Schottky and Frenkel defect?
Schottky defects occur in ionic crystals where the size of anion is almost same with the size of the cation. Frenkel Defect is one type of point defect where an atom (better to say ion, especially cation) leaves its original lattice site and occupies an interstitial position on the same crystal.
What is Frenkel defect give example?
Frenkel defects are mostly exhibited in ionic solids where the smaller ion (usually the cation) is dislocated. Some examples include AgBr, ZnS, AgCl, and AgI. Here the defect occurs mainly due to the smaller size of Zn2+ and Ag+ ions.
What are the conditions for Schottky defect?
Characteristics Of Schottky Defect
- There is a very small difference in size between cation and anion.
- Cation and anion both leave the solid crystal.
- Atoms also move out of the crystal permanently.
- Generally two vacancies are formed.
- As for the density of the solid it decreases considerably.
What is a Schottky Rectifier?
The Schottky diode or Schottky Barrier Rectifier is named after the German physicist “Walter H. Schottky”, is a semiconductor diode designed with a metal by the semiconductor junction. It has a low-forward voltage drop and a very rapid switching act. Actually, it is one of the oldest semiconductor devices in reality.
What’s the difference between a diode and a rectifier?
A diode is an electronic component that allows the current to flow in only one direction. It is a two-terminal semiconductor device. The rectifier is a device that is used to convert an AC voltage to a DC voltage.
Why do we use Schottky diode?
What are Schottky Diode characteristics and applications? Schottky diodes are used for their low turn-on voltage, fast recovery time and low-loss energy at higher frequencies. These characteristics make Schottky diodes capable of rectifying a current by facilitating a quick transition from conducting to blocking state.
What is the difference between a Zener diode and a Schottky diode?
As their switching speed is very high, Schottky diodes recover very fast when the current reverses, resulting in only a very small reverse current overshoot. A special type of diode, called the Zener diode, blocks the current through it up to a certain voltage when reverse biased.
What is the difference between a diode and a Zener diode?
A diode is a semiconductor device which conducts in one direction only. A Zener diode is a semiconductor device which conducts in forward biased as well as reversed biased. A normal diode if operated in reversed biased will get destroyed.
What is a Zener diode used for?
Zener diodes are used for voltage regulation, as reference elements, surge suppressors, and in switching applications and clipper circuits. The load voltage equals breakdown voltage VZ of the diode. The series resistor limits the current through the diode and drops the excess voltage when the diode is conducting.
How do you identify a zener diode?
Zeners may be indistinguishable from regular diodes. Zener diodes may have a dark plastic casing with a dark stripe, which is the same coloring as that of other diodes. Many other zener diodes are copper colored, and are enclosed in a glass casing with a white or black or blue stripe.
What happens when zener diode is connected in series?
In this case, one Zener diode will be forward biased while the other is reverse biased. In the end-to-end arrangement, the cathode of one diode is connected to the anode of another diode, so both will be forward biased or both will be reverse biased. End-to-end and back-to-back current-voltage diodes in series.
How do you identify a 12v zener diode?
Note place a diode across the meter probes. One way they’ll read a low voltage (under 1V). The other way, if they read less than 18V then the diode is likely to be a zener diode. The voltage you see on the multimeter is the zener diode voltage.
What is Zener diode with diagram?
A Zener diode is a silicon semiconductor device that permits current to flow in either a forward or reverse direction. The diode consists of a special, heavily doped p-n junction, designed to conduct in the reverse direction when a certain specified voltage is reached.
What is Zener diode characteristics?
A Zener diode operates just like a normal diode when it is forward-biased. However, when connected in reverse biased mode, a small leakage current flows through the diode. As the reverse voltage increases to the predetermined breakdown voltage (Vz), current starts flowing through the diode.
How many types of Zener diode are there?
The two types of diode are in fact constructed the same way and both effects are present in diodes of this type. In silicon diodes up to about 5.6 volts, the Zener effect is the predominant effect and shows a marked negative temperature coefficient.
What is the most useful characteristic of a Zener diode?
The most useful characteristic of a Zener diode is a constant voltage drop under conditions of varying current. (E6B01) This makes it useful in voltage regulator circuits. Another example is the varactor diode. The varactor diode is a semiconductor device designed for use as a voltage-controlled capacitor.
What happens if Zener diode is forward biased?
When Zener diode is biased in the forward direction it behaves like a normal signal diode passing the current increasing linearly with voltage, but as soon as a reverse voltage applied across the Zener diode attains the breakdown voltage of the device, a large current starts to flow through the diode.