Brian Kidd Ridley (born 2 March 1931) is a British
solid-state physicist
Solid-state physics is the study of rigid matter, or solids, through methods such as quantum mechanics, crystallography, electromagnetism, and metallurgy. It is the largest branch of condensed matter physics. Solid-state physics studies how t ...
specialising in semiconductor theory. He is an emeritus professor at the
University of Essex
The University of Essex is a public research university in Essex, England. Established by royal charter in 1965, Essex is one of the original plate glass universities. Essex's shield consists of the ancient arms attributed to the Kingdom of Es ...
.
Education
Ridley was educated at the
University of Durham
, mottoeng = Her foundations are upon the holy hills ( Psalm 87:1)
, established = (university status)
, type = Public
, academic_staff = 1,830 (2020)
, administrative_staff = 2,640 (2018/19)
, chancellor = Sir Thomas Allen
, vice_ch ...
. He received a BSc degree in physics in 1953 and completed his doctoral studies in 1957.
Career
Ridley began his career as a research physicist in the solid-state physics division of the
Mullard
Mullard Limited was a British manufacturer of electronic components. The Mullard Radio Valve Co. Ltd. of Southfields, London, was founded in 1920 by Captain Stanley R. Mullard, who had previously designed thermionic valves for the Admiral ...
Research Laboratories in
Redhill, Surrey
Redhill () is a town in the borough of Reigate and Banstead within the county of Surrey, England. The town, which adjoins the town of Reigate to the west, is due south of Croydon in Greater London, and is part of the London commuter belt. The ...
(1956–1964). In 1964, he joined the
University of Essex
The University of Essex is a public research university in Essex, England. Established by royal charter in 1965, Essex is one of the original plate glass universities. Essex's shield consists of the ancient arms attributed to the Kingdom of Es ...
as a lecturer in physics, later becoming a senior lecturer (1967), reader (1971) and finally professor of physics (1984), before retiring in 2008. He has held distinguished visiting professorial appointments at
Cornell University
Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to ...
(1967) and the
Danish Technical University
The Technical University of Denmark ( da, Danmarks Tekniske Universitet), often simply referred to as DTU, is a polytechnic university and school of engineering. It was founded in 1829 at the initiative of Hans Christian Ørsted as Denmark's fir ...
(1969), and has held research appointments at
Princeton
Princeton University is a private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth as the College of New Jersey, Princeton is the fourth-oldest institution of higher education in the United States and one of the ni ...
,
Stanford
Stanford University, officially Leland Stanford Junior University, is a private research university in Stanford, California. The campus occupies , among the largest in the United States, and enrolls over 17,000 students. Stanford is consider ...
Oregon
Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idah ...
, and
Eindhoven
Eindhoven () is a city and municipality in the Netherlands, located in the southern province of North Brabant of which it is its largest. With a population of 238,326 on 1 January 2022,
Research
Ridley has conducted work on
negative differential resistance
In electronics, negative resistance (NR) is a property of some electrical circuits and devices in which an increase in voltage across the device's terminals results in a decrease in electric current through it.
This is in contrast to an ordina ...
Gunn diode
A Gunn diode, also known as a transferred electron device (TED), is a form of diode, a two-terminal semiconductor electronic component, with negative resistance, used in high-frequency electronics. It is based on the "Gunn effect" discovered in ...
s, and he was the first to discover the
impurity
In chemistry and materials science, impurities are chemical substances inside a confined amount of liquid, gas, or solid, which differ from the chemical composition of the material or compound. Firstly, a pure chemical should appear thermody ...
barrier mechanism for NDR, and to demonstrate its existence in
germanium
Germanium is a chemical element with the symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid in the carbon group that is chemically similar to its group neighbo ...
. He was also the first to describe the consequences of NDR instabilities in terms of propagating dipole domains and
current filament
A current filament is an inhomogeneity in the current density distribution lateral to the direction of the current flow (that is, orthogonal to the current density vector
Vector most often refers to:
*Euclidean vector, a quantity with a magni ...
s. The existence of these
nonlinear
In mathematics and science, a nonlinear system is a system in which the change of the output is not proportional to the change of the input. Nonlinear problems are of interest to engineers, biologists, physicists, mathematicians, and many other ...
entities has been verified in a wide variety of solids. His work on acoustoelectric instabilities led to his invention of the microsonic analogue of the
laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The firs ...
. He has made original contributions to the theory of electron transitions in solids, particularly impurity scattering and multiphonon processes. This work is the subject of his monograph ''Quantum Processes in Semiconductors'', widely used as a reference text.
He wrote three popular books, ''Time, Space and Things'' (1976), which has been translated into multiple languages, ''The Physical Environment'' (1979) and '' On Science'' (2001).
Awards and honours
Ridley was elected a Fellow of the Royal Society (FRS) in 1994. One or more of the preceding sentences may incorporate text from the royalsociety.org website where "all text published under the heading 'Biography' on Fellow profile pages is available under Creative Commons Attribution 4.0 International License." In 2001, the
Institute of Physics
The Institute of Physics (IOP) is a UK-based learned society and professional body that works to advance physics education, research and application.
It was founded in 1874 and has a worldwide membership of over 20,000. The IOP is the Physica ...
awarded him the
Dirac Medal
The Dirac Medal is the name of four awards in the field of theoretical physics, computational chemistry, and mathematics, awarded by different organizations, named in honour of Professor Paul Dirac, one of the great theoretical physicists of the 2 ...
in recognition of his four-decade long ''influence on the semiconductor theory''.