Walter H(ouser) Brattain

US physicist, born in Amoy, SE China, where his father was a teacher. He grew up on a cattle ranch in the State of Washington, and studied at the universities of Oregon and Minnesota. In 1929 he joined Bell Telephone Laboratories, where he worked as a research physicist on the surface properties of semiconductors. With Bardeen and Shockley he developed the point-contact transistor, using a thin germanium crystal. He shared the Nobel Prize for Physics in 1956.

Walter Houser Brattain (February 10, 1902 – October 13, 1987) was a physicist at Bell Labs who, along with John Bardeen and William Shockley invented the transistor.

Brattain's concerns at Bell Laboratories in the years before World War II were first in the surface physics of tungsten and later in the surfaces of the semiconductors cuprous oxide and silicon.

Following the war, Brattain returned to Bell Laboratories and soon joined the semiconductor division of the newly-organized Solid State Department of the laboratories. William Shockley was the director of the semiconductor division, and early in 1946 he initiated a general investigation of semiconductors that was intended to produce a practical solid state amplifier.

Crystals of pure semiconductors (such as silicon or germanium) are very poor conductors at ambient temperatures because the energy that an electron must have in order to occupy a conduction energy level is considerably greater than the thermal energy available to an electron in such a crystal. Heating a semiconductor can excite electrons into conduction states, but it is more practical to increase conductivity by adding impurities to the crystal. A crystal may be doped with a small amount of an element having more electrons than the semiconductor, and those excess electrons will be free to move through the crystal; such a crystal is an n-type semiconductor. One may also add to the crystal a small amount of an element having fewer electrons than the semiconductor, and the electron vacancies, or holes, so introduced will be free to move through the crystal like positively-charged electrons; such a doped crystal is a p-type semiconductor.

At the surface of a semiconductor the level of the conduction band can be altered, which will increase or decrease the conductivity of the crystal. Junctions between metals and n-type or p-type semiconductors, or between the two types of semiconductors, have asymmetric conduction properties, and semiconductor junctions can therefore be used to rectify electrical currents.

Semiconductor rectifiers were familiar devices by the end of World War II, and Shockley hoped to produce a new device that would have a variable resistance and hence could be used as an amplifier. The conductivity of the semiconductor changed only by a small fraction of the expected amount when the field was applied, which John Bardeen (another member of Shockley's division) suggested was due to the existence of energy states for electrons on the surface of the semiconductor. Brattain – Biography Nobel Prize in Physics: Laureates