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 At first, when the crystal is withdrawn, its cross –sectional area increase.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

What are end-terminations, What are end-terminations? Again, we get our...

What are end-terminations? Again, we get ourselves in an area where many confusion and controversy are the order of the day. Several American institutions have tried to set sta

Illustrate what is larger the force the earth exerts on you, Q. Illustrate ...

Q. Illustrate what is larger the force the earth exerts on you or the force you exert on the earth? Answer:- A non-scientist's preliminary stab at this If you are talking

Surface tension, what are the advantages of surface tension

what are the advantages of surface tension

What is tremendous decrease when metal become superconductor, When a metal ...

When a metal becomes a superconductor, there is a tremendous decrease in it's: a) Total volume b) Electrical resistance c) Length d) Density Ans: While a

air gap in between the parallel plates, How is that circuit wont be broken...

How is that circuit wont be broken even there is an air gap in between the parallel plates? Ans) In AC circuit capacitor offers resistance to current as aresistor would do in DC.

Find capacitance, For a parallel-plate capacitor with plate area "A" and pl...

For a parallel-plate capacitor with plate area "A" and plate separation "d", the capacitance is proportional to which of the following? a) A divided by d squared b) A tim

Conservation of angular momentum, A figure skater who while spinning in pla...

A figure skater who while spinning in place drag her arms in to increase her rotational speed is most closely exhibiting which of the following Answer:- a) Conservation of

In what direction does benito pull if the game is tied, Five people are pla...

Five people are playing tug-of-war. Anders and Alyson pull to the right with 45 N and 35 N, respectively. Calid and Marisol pull to the left with 53 N and 38 N, respectively.

Claculate deviation, A ray of light is incident normally on an equilateral ...

A ray of light is incident normally on an equilateral prism of refractive index 3/2 calculate devition. Ans) since the prism is equilateral therefore angle of prism is 60 0 =

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