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Epitaxy, Berry's Rotation, Polarization, IR spectroscopy, Rochow

This is a past exam for practice. Please complete question 5 only.

20 5. Write brief notes on any four of the following:
a. Metal-organic vapor phase epitaxy
b. Berry's rotation.
c. Effect of polarization on melting points
d. IR spectroscopy as a tool for structure determination of inorganic compounds
e. Rochow process

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Metal Organic Vapor Phase Epitaxy (MOVPE) is another key enabling technology for growing epiwafers of III-V compounds.MOVPE relies on volatile metal-organic compounds, such as trimethyl gallium or trimethyl aluminum, that act as precursors for the material in thin films. The materials grown contain some combination of gallium, indium, aluminum, nitrogen, phosphorus or arsenic. The process consists of transporting the precursors via a carrier gas to a hot zone within a growth chamber. These precursors either dissociate or react with another compound to produce thin films consisting of a single element or of a compound. Varying the composition of deposited materials and doping in the epilayers produces the end device. MOVPE technology is most commonly used to grow materials for high brightness light-emitting devices (LEDs). Other applications include high-efficiency solar cells and solid state semiconductor lasers used in broadband communication, especially for fiber-optic networks.

Any 'vector' object which is parallel-trasported along a path back to the original place, may acquire an angle with respect to its initial direction prior to transport. This angle is a geometric property. Such rotation angles of geometrical origin are known as Berry phases. "Phase" is used meaning just "angle" for whatever possible argument of sin(·) or cos(·) or exp(i ·). M. Berry postulated a very influential formal systematization of the closed-path geometric phase in quantum mechanical problems. Berry phases do not appear only in everyday experience of geometrical vectors. The ingredients ...