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 At first, when the crystal is withdrawn, its cross –sectional area increase.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 length required for the tube heat exchanger, A concentric tub...

A concentric tube heat exchanger is comprised of a thin wall inner tube of 25.4 mm diameter and an outer tube of 47 mm diameter. The heat exchanger is used for cooling lubricating

Give the graphical representation of plane polarized light, Give the graphi...

Give the graphical representation of the end on view of plane polarized light and unpolarized light.

Explain the change in the thermal energy of the water, A cylinder having 1....

A cylinder having 1.00 g of water at the boiling point is heated until all the water turns into steam. The expanding steam pushes a piston 0.365 m. There is a 215-N frictio

Unit of impulse, UNIT: SI unit of impulse is NS (Newton x Second) or ...

UNIT: SI unit of impulse is NS (Newton x Second) or kgms -1

State the characteristics of antennas isolated, a. Explain the following te...

a. Explain the following terms in connection with electro-magnetic waves: (i) Transverse waves (ii) Power density (iii) Wave impedance (iv) Polarization b. State the chara

Give the basic construction of pentode, Give the basic construction of pent...

Give the basic construction of pentode Ans: Construction of Pentode:   Constructional details of a typical pentode are demonstrated in fig. (a)  and  fig. (b)  Pentode comp

A lever of the second class, A lever of the second class Use a uniform ...

A lever of the second class Use a uniform wooden bar about 1 m long, 4 cm wide and 5 mm thick. Drill a hole near single end, in the centre of the width dimension. Also drill a

Motion, a ball is thrown up and come in the hands of thrower find heigth

a ball is thrown up and come in the hands of thrower find heigth

Telescope, Working of terrestrial telescope

Working of terrestrial telescope

Reverse osmosis, Select one membrane industrial separation application for...

Select one membrane industrial separation application for (i) reverse osmosis (RO), (ii) ultrafiltration (UF) and (iii) microfiltration (MF) (at least one of the three (in total

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