Semiconductors
The Foundation of Modern Electronics
What is a Semiconductor:
Semiconductor materials are materials with that allow electricity to pass through due to electron flow. In contrast, normal conductors have ionic conductivity. Various elements are semiconductors. One of the first to be experimented with was germanium (Ge) (Element # 32). Silicon, Gallium are more well known semiconductors.
Semiconductors are so universal in application due to the ability of humans to precisely control how these materials conduct electricity: by controlling crystal size of the element and doping one can achieve desired resistively.
Doping is introducing certain impurities into a pure sample of semiconductor to achieve desired properties. Doping a semiconductor to high levels makes the material act more like a conductor, this is called degenerate. A lightly doped semiconductor is called extrinsic.Example: William Morris, John Harnden and Fracois Martzloff created the MOV (metal oxide varistor) which uses gallium/arsenic compound. The goal of the team was to create a chip that would allow 125 Volts from the power grid to get through (to your computer for instance) but not allow voltages greater than ~130 Volts. This would prevent voltage spikes (transients) from destroying other semiconductors (like the silicon micro processors) which are very sensitive to voltage and current. The team got the material to do this by growing the right sized gallium crystals and doping it with the right recipe of impurities.
Applications:
There are too many applications of the material to list, however you can click on the following links to see related pages and videos on the Edison Tech Center web site.
How the Semiconductor Laser Works CMOS photo imaging Chip The Metal Oxide Varistor (MOV) Purifying Germanium with Dr. Robert Hall LED (Light Emitting Diode) Solid State switches in HVDC
Featured Pioneers:
Bell Labs:
John Bardeen (Transistor)
William Shockley (Transistor)
Walter Brattain (Transistor)
Fred Seitz (solid state physics)
General Electric:
Robert N. Hall (Semiconductor laser and power conditioning)
Nick Holonyack (Red LED)Bernie Bedford (SVC - Static VAR Compensator)
Bill Gutzwiller (SCR - Silicon Controlled Rectifier)
John Harnden Jr. (GEMOV - Metal Oxide Varistor and power conditioning)
Bill Morris (GEMOV - Metal Oxide Varistor)
Texas Instruments:Gary Pittman (First LED, infrared)
Bob Biard (First LED, infrared)Monsanto:
George Craford (Yellow LED)
Independent:
Shuji Nakamura (Blue LED)
Featured videos on the history of semiconductors:
The GE Semiconductor Business, Oral History with Dr. Oliver Winn - Former manager of the General Electric microprocessing division
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