Surface-barrier transistor
Encyclopedia
The surface-barrier transistor is a type of transistor
developed by Philco
in 1953 as an improvement to the alloy-junction transistor
and the earlier point-contact transistor
. Like the modern schottky transistor, it offered much higher speed than earlier transistors and used metal
–semiconductor
junctions (instead of semiconductor–semiconductor junction
s), but unlike the schottky transistor, both junctions were metal–semiconductor junctions.
It consists of a semiconductor
crystal forming the base, into which a pair of wells are etched on opposite sides and electroplated
to form the metal emitter and collector surface-barrier contacts.
The surface-barrier transistor became obsolete in the early 1960s with the development of the diffusion transistor
.
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
developed by Philco
Philco
Philco, the Philadelphia Storage Battery Company , was a pioneer in early battery, radio, and television production as well as former employer of Philo Farnsworth, inventor of cathode ray tube television...
in 1953 as an improvement to the alloy-junction transistor
Alloy-junction transistor
The germanium alloy-junction transistor, or alloy transistor, was an early type of bipolar junction transistor, developed at General Electric and RCA in 1951 as an improvement over the earlier grown-junction transistor....
and the earlier point-contact transistor
Point-contact transistor
A point-contact transistor was the first type of solid-state electronic transistor ever constructed. It was made by researchers John Bardeen and Walter Houser Brattain at Bell Laboratories in December 1947. They worked in a group led by physicist William Bradford Shockley...
. Like the modern schottky transistor, it offered much higher speed than earlier transistors and used metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
–semiconductor
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
junctions (instead of semiconductor–semiconductor junction
P-n junction
A p–n junction is formed at the boundary between a P-type and N-type semiconductor created in a single crystal of semiconductor by doping, for example by ion implantation, diffusion of dopants, or by epitaxy .If two separate pieces of material were used, this would...
s), but unlike the schottky transistor, both junctions were metal–semiconductor junctions.
It consists of a semiconductor
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
crystal forming the base, into which a pair of wells are etched on opposite sides and electroplated
Electroplating
Electroplating is a plating process in which metal ions in a solution are moved by an electric field to coat an electrode. The process uses electrical current to reduce cations of a desired material from a solution and coat a conductive object with a thin layer of the material, such as a metal...
to form the metal emitter and collector surface-barrier contacts.
The surface-barrier transistor became obsolete in the early 1960s with the development of the diffusion transistor
Diffusion transistor
A diffusion transistor is any transistor formed by diffusing dopants into a semiconductor substrate. Diffusion transistors include some types of both bipolar junction transistors and field-effect transistors...
.
External links
- Transistors, A. A. Vxrela, United States Patent number: 2843809
- Transistor Process and Apparatus, Jjotlovarir V.Gappert, United States Patent number: 2876184
- Transistor Museum: Historic Transistor Photo Gallery: Philco A01
- Transistor Museum: Historic Transistor Photo Gallery: Surface Barrier Transistor