Question

Of the following DIODES:
• PIN DIODE
• TUNNEL DIODE
• GUN DIODE
• LASER DIODE

Research:
a) Specific construction characteristics
b) Function description
c) Symbol
d) Main applications

Thank a lot.

Answer 1

a)PIN Diode

The improved version of the normal P-N junction diode gives the PIN diode. In PIN diode doping is not necessary. The intrinsic material means the material which has no charge carriers is inserted between the P and N regions which increase the area of depletion layer.

When we apply forward bias voltage the holes and electrons will pushed into the intrinsic layer. At some point due to this high injection level the electric field will conduct through the intrinsic material also. This field made the carriers to flow from two regions. The symbol of PIN diode is as shown below:

PIN Diode Applications:

1. Rf Switches: Pin diode is used for both signal and component selection. For example pin diodes acts as range-switch inductors in low phase noise oscillators.

2. Attenuators: it is used as bridge and shunt resistance in bridge-T attenuator.

3. Photo Detectors: it detects x-ray and gamma ray photons.

b)Tunnel Diode

It is used as high speed switch, of order nano-seconds. Due to tunneling effect it has very fast operation in microwave frequency region. It is a two terminal device in which concentration of dopants is too high.

The transient response is being limited by junction capacitance plus stray wiring capacitance. Mostly used in microwave oscillators and amplifiers. It acts as most negative conductance device. Tunnel diodes can be tuned in both mechanically and electrically. The symbol of tunnel diode is as shown below.

> or DA

Tunnel Diode Applications

1. Oscillatory circuits.
2. Microwave circuits.
3. Resistant to nuclear radiation.

c)Gunn Diode

Gunn diode is fabricated with n-type semiconductor material only. The depletion region of two N-type materials is very thin. When voltage increases in the circuit the current also increases. After certain level of voltage the current will exponentially decrease thus this exhibits the negative differential resistance.

It has two electrodes with Gallium Arsenide and Indium Phosphide due to these it has negative differential resistance. It is also termed as transferred electron device. It produces micro wave RF signals so it is mainly used in Microwave RF devices. It can also use as an amplifier. The symbol of Gunn diode is shown below:

Applications:

Gunn Diodes are used as oscillators and Amplifiers. They are used in radio communication, military and commercial radar sources. Gunn diodes are used as fast controlling equipment in microelectronics for modulation of laser beams. It is used in tachometers.

d)Laser Diode

Similar to LED in which active region is formed by p-n junction. Electrically laser diode is p-i-n diode in which the active region is in intrinsic region. Used in fiber optic communications, barcodereaders, laser pointers, CD/DVD/Blu-ray reading and recording, Laser printing.

Laser Diode Types:

1. Double Heterostructure Laser: Free electrons and holes available simultaneously in the region.
2. Quantum Well Lasers: lasers having more than one quantum well are called multi quantum well lasers.
3. Quantum Cascade Lasers: These are heterojunction lasers which enables laser action at relatively long wavelengths.
4. Separate Confinement Heterostructure Lasers: To compensate the thin layer problem in quantum lasers we go for separate confinement heterostructure lasers.
5. Distributed Bragg Reflector Lasers: It can be edge emitting lasers or VCSELS.

The symbol of the Laser Diode is as shown:

Anode Cathode

Applications:

Laser diodes are the most common type of lasers produced, with a wide range of uses that include fiber optic communications, barcode readers, laser pointers, CD/DVD/Blu-ray disc reading/recording, laser printing, laser scanning and light beam illumination.

Answer 2

I have explained the diode working construction and application below.
PIN Diode A PN Diode is made up of semiconductor Materials. The entransic Semiconductor Seperated by two heavily doped p and n type material The intrinsic layer provides change in properties which compared to normal PN Junction diodo. Operation / Function The pin diode exactly same as a normal diode. It operates in under what is called as high level infection. Its function can be likend to bill up water bucket with side hole. It pour out when water reaches hole level. Once the flooded electrons and holes reach equilibrium pant the diode will conduct carrent When PIN Diode is connected in forward biased the charge carrier is very much higher tha level of intrinsic carriers attention . Thus electric bield assists Speed up the moving of charge. carries from p and n region which is a n quick operation of PiN diode or high freluence operation Symbol anode N cathole to

Main application * Used as voltage rectibier * Used as ideal radio frequency switch. * Used as photo detector * TUNNEL DIODE The tunnel, diode is one of the most commonly used negative conductance diode The concentration of dopants both p andh is very high 1024 1025 m3 the Pn Junction is abrupt. Depletion layer width is small. In carrent voltage character we find negative Slope region when forward blas applied Working When Reverse bias applied fermi level of P becomes higher than n side. Thus tunneling electron from balance band of p side to conduction band on n side with reverse bias Caryent increases - At Forward bias in becomes higher of p side tunnelong from n PA side. The tunneling current is high than unction carrent. Thus FB1 Tunnel corrent 1

Symbol Application * Ideally used in oscillator circuits. * used as resistant to nuclear reaction. GUNN Diode GONN diode also known as Transboered electronic device. It has only No type semi conductor in which electrons are madority Carriers. To generate short microwaves - The central region is active region. which is w-type Grads and epitaxial layer with 8 to to micrometer thickness. Active region is sandwiched between ohmic contacts Working If voltage is applied the most voltage appears across ative region. An increase in Forward voltage increases field strength voltage Greater than threshold Number obeledron decreases with velocity that current decreases.

Thus field strength increased velocity decrease creates negative incremental resistance region. To maintain constant voltage a new slice created at cathode Symbol Anode x cathode Application * Generate brequency from 100 mw suHzho IW 35 GH2. For radio communication. * Used in sensors to detec fres passers & Used for remote vibration detectors and tachometers LASER DIODE The construction of Laser diode is. Similar to LED. It uses gallium arsenide, doped with elements such as silicon to produre - type to N type material. While laser diode has additional active layer of undoped Gallium of bew nanometer thickness and witch between PAN thus layer at which light is produced, como

Working The process of stimulated emission is fundamental for laser action. It is the process 06 photon having exactly same wavelength as light emitted. The laser diode is operated at higher current typically about 10 times greater than LED. The active region of laser diode is in the entrensic region and carriers are pumped unto region from N and p region respectively While initial diode laser research was conducted on simple P-N diode. the carries and photons Contined to maximize chances of recombination and light generation. The laser diodes epitarial structure bormed by crystal growth technique's. The active layer is often consists of quantum wells that provide low threshold carrent and high ebbiciency Symbol Anodelt) 2 cathode (-) Application * Laser diodes used in CD A DVD players * In Industry used for cutting, scribing, welding * It is used in telecom..