Semiconductor Materials:

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Semiconductor Materials
Ge, Si and GaAs
Prepared By Rhowena M. Banuag ICS 30 A
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Obtain the semiconductor materials

• Germanium (Ge)
• Silicon (Si)
• Gallium (Arsenide GaAs)

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Germanium Ge
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Uses

• x-ray lens
• transistor element (doped with arsenic,
  gallium,etc.)
• as an alloying agent
• phosphor in fluorescent lamps
• wide-angle camera lenses and microscope
  objectives
• gamma-radiation detector

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Silicon Si

• a hard, dark grey nonmetal
• makes up about 28 of earths crust and is 2nd
  most abundant element
• occurs in clay granite quartz sand
• pure silicon melts at 1410 degree C

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Uses

• Silicon/plastic fluidic coupler to standard
  capillary tubing. The coupler is fabricated using
  DRIE technology combined with injection-molded
  press fittings.

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• occurs only in combination with other elements,
  chiefly with oxygen as silicon dioxide this
  compound cold silica, is the main ingredient of
  sand
• major ingredient of various minerals that form
  rocks
• used as a semiconductor in transistors

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Gallium Ga
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• It is the only metal, except for mercury,
  caesium, and rubidium, which can be liquid near
  room temperatures this makes possible its use in
  high-temperature thermometers. It has one of the
  longest liquid ranges of any metal and has a low
  vapour pressure even at high temperatures

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Arsenide As
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• Gallium arsenide (GaAS) is capable of converting
  electricity directly into coherent light and is a
  key component of LEDs (light emitting diodes)

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Zone-Refining Process

• a rod of metal is heated near one end so that a
  cross-sectional wafer of molten metal is produced
  that cause impurities to the end.
• -the process can be repeated and the impure
  end is then removed
• - impurity level of less than 1 part in 1
  billion(1 in 1,000,000,000 atom percent) are
  required most for most semiconductor fabrications
  

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Difference

• Polycrystalline crystal
• -atoms are arranged haphazardly (random)
• Single Crystal
• -atoms are arranged symmetrical, uniform,
  geometrical lattice structure

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Zone-Refining Process
Induction heating coils
Quartz Container
Inert gas or vacuum
Molten Region
Graphite boat
High-purity Silicon
Silicon ingot (low-purity level)
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Czochralski Technique

• was developed in 1916 and initially used to
  measure of crystallization rate of metals
• used for producing large single crystals
• The most dominant technique for commercial
  production of most of these materials

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