History of Computers - Semiconductors
Page created by William Brown
Semiconductors are an integral part of today's electronics. Without them, computers would still be operated by vacuum tubes.
Contents
Overview
Semiconductors are found in the 4th family of the periodic table, the elements which have 4 electrons in their outer shell. Their outer electrons allow for a very uniform crystalline structure, demonstrated in carbon such as diamond. The very stable balanced structure causes these crystal structures to be insulators, as there are no free electrons for a current to flow. For a semiconductor to become conductive, the material must be injected with slight impurities, or "doped."[1] The impurities cause either "holes" where there is a lack of electrons in P-type doping, or adds in extra electrons in N-type doping. Silicon is the most commonly used semiconductor, as it is easy to find and notably less expensive than diamond. In a diode the two types of doped silicon are pressed together, which allows a current to pass in only one direction. In transistors, there is a sandwich of either PNP or NPN silicon, where a current cannot flow in either direction unless a smaller normally positive current is running through the center pin.[1] For more info on why the diodes and transistors behave in this way, click here.
Significance
The Semiconductor is extremely important to computers simply because without them, computers as we know them today would not exist. Almost all modern electronic devices use transitors or diodes, technologies made impossible without semiconductive materials. Before semiconductors, computers relied on large vacuum tubes, which posed a size problem. Computers using tube technology took up entire rooms. With semiconductors we now have handheld calculators many times more powerful than those room-sized computers and many times smaller as well.
Links
- http://en.wikipedia.org/wiki/Semiconductor
- http://www.computerhistory.org/semiconductor/timeline/1926-field.html
- http://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci212960,00.html
