Walter Houser Brattain (February 10, 1902 – October 13, 1987) was an American physicist at Bell Labs who, along with John Bardeen and William Shockley, invented the transistor. They shared the 1956 Nobel Prize in Physics for their invention. He devoted much of his life to research on surface states.
Early life and education
He was born to American parents Ross R. Brattain and Ottilie Houser in Amoy, China, where his father was a teacher, on February 10, 1902.[2] He spent the early part of his life in Springfield, Oregon where an elementary school is named in his honor, and Tonasket, Washington in the United States.
He was raised in Tonasket, Washington on a cattle ranch owned by his
parents, and earned his B.A. degree in physics and mathematics at Whitman College in Walla Walla, Washington. Brattain earned that degree in 1924 and an M.A. degree from the University of Oregon in 1926. He then moved eastward, taking his Ph.D. degree in physics at the University of Minnesota
in 1929. Brattain's advisor was John T. Tate Sr., and his thesis was on
electron impact in mercury vapor. In 1928 and 1929 he worked at the National Bureau of Standards in Washington, D.C., and in 1929 was hired by Bell Telephone Laboratories.
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. During World War II Brattain devoted his time to developing
methods of submarine detection under a contract with the National
Defense Research Council at Columbia University.
Career in physics
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. In a rectifier, a voltage bias that produces a
current flow in the low-resistance direction is a forward bias, while a
bias in the opposite direction is a reverse bias.
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. He proposed
a design in which an electric field was applied across the thickness of
a thin slab of a semiconductor. 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.