Crystal growth, Physics

Assignment Help:

 

The fabrication of discrete and integrated circuit solid state devices requires semiconductor crystals with impurity concentrations as low as possible and crystals that contain very few imperfection. A number of laboratory techniques are available for growing high purity semiconductor crystal. The refining of silicon by the Czochralski Technology is the most common method of producing monocrystalline silicon large diameter monocrystalline silicon can be grown with the Czochralski technique. This method involves growing a single crystal ingot from the melt, using solidification on a seed crystal as depicted. Czochralski silicon can be grown with resistivity in the order of 1 to 2mO-cm. Which is sufficient for making of most IC’s; including low to medium power IC’s. Molten Si is held in a quartz crucible in graphite suspected, which is heated by a radio frequency induction coil. A small dislocation free crystal, known as a seed, is lowered to touch the melt and then gradually pulled out of the melt. The seed is rotated in the pulling stage, to get a cylindrical ingot. To suppress evaporation from the melt and prevent oxidation, argon gas is passed through the system. At first, when the crystal is withdrawn, its cross –sectional area increase. It then reaches a constant value determined by the temperature gradients, heat losses and the pull. As the melt solidifies on the crystals, heat of fusion is released and must be away through the crystal. While the rate of pull finds the rate at which latent heat is released. To obtain an ingot with a large cross-sectional area, the pull speed must be slow. The Czochralski technique is also used for growing Gallium; Gallium Arsenide through each case has its own particular requirements. The main drawback of the Czochralski technique is that the final silicon crystal inevitably contains oxygen impurities dissolved from the quartz crystal crucible.

 


Related Discussions:- Crystal growth

Determine the depth of a freshwater lake - sound waves, Sound waves are bei...

Sound waves are being used to determine the depth of a freshwater lake, as shown in the figure below. If the water is 25°C and it takes 1.2 s for the echo to return to the sens

Volume resistance and surface resistance, Volume resistance: The resistanc...

Volume resistance: The resistance provided to the current which flows through the material is called volume resistance. For a cube of unit dimensions this is called volume resisti

How much does the temperature rise, When a driver brakes an automobile, the...

When a driver brakes an automobile, the friction between the brake drums and the brake shoes converts the car's kinetic energy to thermal energy. If a 1450 kg automobile traveling

What are the consequences of dispersion, What are the consequences of dispe...

What are the consequences of dispersion? The main familiar result of dispersion is the splitting up of the composite white light within its constituent colours as into a rainbo

Complementarity principle, Complementarity principle (N. Bohr) The prin...

Complementarity principle (N. Bohr) The principle which a given system cannot exhibit wave-like and particle-like both behaviors at the similar time. i.e., certain experiments

Light coupling, Light coupling: Another way to look at light guiding in...

Light coupling: Another way to look at light guiding in a fibre is to measure the fibre's acceptance angle. This angle is the angle within which the light should enter the fib

Basic elactronics, recombination of electrons and holes impurity semiconduc...

recombination of electrons and holes impurity semiconductor

What is friction - work and energy, what is Friction When we think about ...

what is Friction When we think about friction, there is one more place for energy to go - heat. When you push a book across a table, does the energy of the book change? Not if in

Measuring field strength of permanent magnets, I want to measure H, not B T...

I want to measure H, not B The magnets in question are permanent magnets (large Neo or SmCo magnets), not coils =====================....Steel ____........................____ |.

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd