Silicon

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Silicon

Silicon

Silicon is the raw material most often used in integrated circuit (IC)
fabrication. It is the second most abundant substance on the earth. It is
extracted from rocks and common beach sand and put through an exhaustive
purification process. In this form, silicon is the purist industrial substance
that man produces, with impurities comprising less than one part in a billion.
That is the equivalent of one tennis ball in a string of golf balls stretching
from the earth to the moon.
Semiconductors are usually materials which have energy-band gaps smaller
than 2eV. An important property of semiconductors is the ability to change
their resistivity over several orders of magnitude by doping. Semiconductors
have electrical resistivities between 10-5 and 107 ohms. Semiconductors can be
crystalline or amorphous. Elemental semiconductors are simple-element
semiconductor materials such as silicon or germanium.
Silicon is the most common semiconductor material used today. It is used
for diodes, transistors, integrated circuits, memories, infrared detection and
lenses, light-emitting diodes (LED), photosensors, strain gages, solar cells,
charge transfer devices, radiation detectors and a variety of other devices.
Silicon belongs to the group IV in the periodic table. It is a grey brittle
material with a diamond cubic structure. Silicon is conventionally doped with
Phosphorus, Arsenic and Antimony and Boron, Aluminum, and Gallium acceptors.
The energy gap of silicon is 1.1 eV. This value permits the operation of
silicon semiconductors devices at higher temperatures than germanium.
Now I will give you some brief history of the evolution of electronics
which will help you understand more about semiconductors and the silicon chip.
In the early 1900's before integrated circuits and silicon chips were invented,
computers and radios were made with vacuum tubes. The vacuum tube was invented
in 1906 by Dr.Lee DeForest. Throughout the first half of the 20th century,
vacuum tubes were used to conduct, modulate and amplify electrical signals.
They made possible a variety of new products including the radio and the
computer. However vacuum tubes had some inherent problems. They were bulky,
delicate and expensive, consumed a great deal of power, took time to warm up,
got very hot, and eventually burned out. The first digital computer contained
18,000 vacuum tubes, weighed 50 tins, and required 140 kilowatts of power.
By the 19

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