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 At first, when the crystal is withdrawn, its cross –sectional area increase.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

Experiment of heater, Heater Another form of heater can be made from an...

Heater Another form of heater can be made from an old oil tin. Iron wire is wrapped round a test tube and twisted to form a handle.

Electric force dipole, An infinite line of positive charge lies along the y...

An infinite line of positive charge lies along the y axis, with charge density ? = 1.90 µC/m. A dipole is placed with its midpoint along the x axis at x = 22.00 cm. The dipole cons

Kohlrauschs law, Kohlrausch's law (F. Kohlrausch): If a salt is dissol...

Kohlrausch's law (F. Kohlrausch): If a salt is dissolved into water, the conductivity of the solution is the total of two values one based on the positive ions & the other dep

Roller Coaster Physics, A 30-g car rolls from a hill 12 cm high and is trav...

A 30-g car rolls from a hill 12 cm high and is traveling at 154 cm/s as it travels along a 275 cm horizontal track. What is the momentum of the car?

Dipole moment, It is the product of either change in an electric dipole wit...

It is the product of either change in an electric dipole with the distance separating them.

Electric and magnetic fields of an oscillating charge, Electric and Magneti...

Electric and Magnetic Fields of an Oscillating Charge A 3 dimensional animation of the "far" fields of an oscillating charge. Electromagnetic radiation (EM radiation or EMR) is

Circular motion, what happens to a conical pendulum when the bob splits int...

what happens to a conical pendulum when the bob splits into two parts such that one part remains attached to the string?

Determine the charge on each capacitor, For the arrangement shown in Figure...

For the arrangement shown in Figure find (a) the equivalent capacitance of the circuit, (b) the voltage across QR, and (c) the charge on each capacitor

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