Herbert Kroemer

Herbert Kroemer (born August 25, 1928), a professor of electrical and computer engineering at the University of California, Santa Barbara, received his Ph.D. in theoretical physics in 1952 from the University of Göttingen, Germany, with a dissertation on hot electron effects in the then-new transistor, setting the stage for a career in research on the physics of semiconductor devices. In 2000, Kroemer, along with Zhores I. Alferov, was awarded the Nobel Prize in Physics "for developing semiconductor heterostructures used in high-speed- and opto-electronics". The other co-recipient of the Nobel Prize was Jack Kilby for his invention and development of integrated circuits and micro-chips.

He worked in a number of research laboratories in Germany and the United States and taught electrical engineering at the University of Colorado from 1968 to 1976. He joined the UCSB faculty in 1976, focusing its semiconductor research program on the emerging compound semiconductor technology rather than on mainstream silicon technology.

Kroemer was elected as a member of the National Academy of Engineering in 1997 and the National Academy of Sciences in 2003. He always preferred to work on problems that are ahead of mainstream technology. In the 1950s, he invented the drift transistor and was the first to point out that advantages could be gained in various semiconductor devices by incorporating heterojunctions. Most notably, in 1963 he proposed the concept of the double-heterostructure laser, which is now a central concept in the field of semiconductor lasers. Kroemer became an early pioneer in molecular beam epitaxy, concentrating on applying the technology to untried new materials.

Along with Charles Kittel he co-authored the popular textbook Thermal Physics, first published in 1980, and still used today. He is also the author of the textbook Quantum Mechanics for Engineering, Materials Science and Applied Physics.[2]

Kroemer is an atheist.[3]

Herbert Kroemer
Herbert Kroemer (cropped)
Herbert Kroemer in 2008
BornAugust 25, 1928 (age 90)
ResidenceUnited States
United States
Alma materUniversity of Jena
University of Göttingen
Known forDrift-field transistor
Double-heterostructure laser
Heterojunction bipolar transistor
AwardsJ J Ebers Award (1973)
Humboldt Research Award (1994)
Nobel Prize in Physics (2000)
IEEE Medal of Honor[1](2002)
Scientific career
FieldsElectrical Engineering, Applied Physics
InstitutionsFernmeldetechnisches Zentralamt
RCA Laboratories
Varian Associates
University of Colorado
University of California, Santa Barbara
Doctoral advisorFritz Sauter
InfluencesFriedrich Hund
Fritz Houtermans

See also


  1. ^ "Herbert Kroemer". IEEE Global History Network. IEEE. Retrieved 10 August 2011.
  2. ^ H. Kroemer, Quantum Mechanics, Prentice Hall (1994)
  3. ^ Kroemer, Herbert. "Herbert Kroemer – Science Video Interview". Interviewer: "You have no belief in a afterlife?" Kroemer: "That's correct." Interviewer: "...You don't see the evidence of a designer?" Kroemer: "No, I don't." Interviewer: "Could you say more about it?" Kroemer: "I think it's just wishful thinking."

External links

1928 in Germany

Events in the year 1928 in Germany.

2000 in science

The year 2000 in science and technology involved some significant events.

Aldert van der Ziel

Aldert van der Ziel, (12 December 1910, Zandeweer – 20 January 1991, Minneapolis), was a Dutch physicist who studied electronic noise processes in materials such as semiconductors and metals.

Drift-field transistor

The drift-field transistor, also called the drift transistor or graded base transistor, is a type of high-speed bipolar junction transistor having a doping-engineered electric field in the base to reduce the charge carrier base transit time.

Invented by Herbert Kroemer at the Central Bureau of Telecommunications Technology of the German Postal Service, in 1953, it continues to influence the design of modern high-speed bipolar junction transistors.

Early drift transistors were made by diffusing the base dopant in a way that caused a higher doping concentration near the emitter reducing towards the collector.This graded base happens automatically with the double diffused planar transistor (so they aren't usually called drift transistors).


A heterojunction is the interface that occurs between two layers or regions of dissimilar crystalline semiconductors. These semiconducting materials have unequal band gaps as opposed to a homojunction. It is often advantageous to engineer the electronic energy bands in many solid-state device applications, including semiconductor lasers, solar cells and transistors ("heterotransistors") to name a few. The combination of multiple heterojunctions together in a device is called a heterostructure, although the two terms are commonly used interchangeably. The requirement that each material be a semiconductor with unequal band gaps is somewhat loose, especially on small length scales, where electronic properties depend on spatial properties. A more modern definition of heterojunction is the interface between any two solid-state materials, including crystalline and amorphous structures of metallic, insulating, fast ion conductor and semiconducting materials.

In 2000, the Nobel Prize in physics was awarded jointly to Herbert Kroemer of the University of California, Santa Barbara, California, USA and Zhores I. Alferov of Ioffe Institute, Saint Petersburg, Russia for "developing semiconductor heterostructures used in high-speed-photography and opto-electronics".

Heterojunction bipolar transistor

The heterojunction bipolar transistor (HBT) is a type of bipolar junction transistor (BJT) which uses differing semiconductor materials for the emitter and base regions, creating a heterojunction. The HBT improves on the BJT in that it can handle signals of very high frequencies, up to several hundred GHz. It is commonly used in modern ultrafast circuits, mostly radio-frequency (RF) systems, and in applications requiring a high power efficiency, such as RF power amplifiers in cellular phones. The idea of employing a heterojunction is as old as the conventional BJT, dating back to a patent from 1951. Detailed theory of heterojunction bipolar transistor was developed by Herbert Kroemer in 1957.

Humboldt Prize

The Humboldt Prize, also known as the Humboldt Research Award, is an award given by the Alexander von Humboldt Foundation of Germany to internationally renowned scientists and scholars who work outside of Germany. The prize is currently valued at €60,000 with the possibility of further support during the prize winner's life. Up to one hundred such awards are granted each year. Nominations must be submitted by established academics in Germany.

The award is named after the late Prussian naturalist and explorer Alexander von Humboldt.

IEEE Medal of Honor

The IEEE Medal of Honor is the highest recognition of the Institute of Electrical and Electronics Engineers (IEEE). It has been awarded since 1917, when its first recipient was Major Edwin H. Armstrong. It is given for an exceptional contribution or an extraordinary career in the IEEE fields of interest. The award consists of a gold medal, bronze replica, certificate and honorarium. The Medal of Honor may only be awarded to an individual.

The medal was created by the Institute of Radio Engineers (IRE) as the IRE Medal of Honor. It became the IEEE Medal of Honor when IRE merged with the American Institute of Electrical Engineers (AIEE) to form the IEEE in 1963. It was decided that IRE's Medal of Honor would be presented as IEEE's highest award, while the Edison Medal would become IEEE's principal medal.

Ten persons with an exceptional career in electrical engineering received both the IEEE Edison Medal and the IEEE Medal of Honor, namely Edwin Howard Armstrong, Ernst Alexanderson, Mihajlo Pupin, Arthur E. Kennelly, Vladimir K. Zworykin, John R. Pierce, Sidney Darlington, Nick Holonyak, Robert H. Dennard, Dave Forney, and Kees Schouhamer Immink.

J. J. Ebers Award

The J J Ebers Award was established in 1971 to foster progress in electron devices. It commemorates Jewell James Ebers, whose contributions, particularly to transistors, shaped the understanding and technology of electron devices. It is presented annually to one or more individuals who have made either a single or a series of contributions of recognized scientific, economic, or social significance in the broad field of electron devices. The recipient (or recipients) is awarded a certificate and check for $5,000, presented at the International Electron Devices Meeting.


Krömer, Kroemer may refer to:

Herbert Kroemer (born 1928), a professor of electrical and computer engineering

24751 Kroemer (1992 SS24), a main-belt asteroid discovered on 1992

List of Nobel laureates affiliated with the University of California, Santa Barbara

The Nobel Prizes are awarded annually by the Royal Swedish Academy of Sciences, the Karolinska Institute, and the Norwegian Nobel Committee to individuals who make outstanding contributions in the fields of chemistry, physics, literature, peace, and physiology or medicine. They were established by the 1895 will of Alfred Nobel, which dictates that the awards should be administered by the Nobel Foundation. Another prize, the Nobel Memorial Prize in Economic Sciences, was established in 1968 by the Sveriges Riksbank, the central bank of Sweden, for contributors to the field of economics. Each prize is awarded by a separate committee; the Royal Swedish Academy of Sciences awards the Prizes in Physics, Chemistry, and Economics, the Karolinska Institute awards the Prize in Physiology or Medicine, and the Norwegian Nobel Committee awards the Prize in Peace. Each recipient receives a medal, a diploma and a cash prize that has varied throughout the years. In 1901, the winners of the first Nobel Prizes were given 150,782 SEK, which is equal to 7,731,004 SEK in December 2007. In 2008, the winners were awarded a prize amount of 10,000,000 SEK. The awards are presented in Stockholm in an annual ceremony on December 10, the anniversary of Nobel's death.

List of members of the National Academy of Sciences (Applied physical sciences)

This list is a subsection of the List of members of the National Academy of Sciences, which includes approximately 2,000 members and 350 foreign associates of the United States National Academy of Sciences, each of whom is affiliated with one of 31 disciplinary sections. Each person's name, primary institution, and election year are given.

Orders of magnitude (probability)

This page lists events in order of increasing probability, grouped by orders of magnitude. These probabilities were calculated given assumptions detailed in the relevant articles and references. For example, the probabilities of obtaining the different poker hands assume that the cards are dealt fairly.

Ridley–Watkins–Hilsum theory

In solid state physics the Ridley–Watkins–Hilsum theory (RWH) explains the mechanism by which differential negative resistance is developed in a bulk solid state semiconductor material when a voltage is applied to the terminals of the sample. It is the theory behind the operation of the Gunn diode as well as several other microwave semiconductor devices, which are used practically in electronic oscillators to produce microwave power. It is named for British physicists Brian Ridley, Tom Watkins and Cyril Hilsum who wrote theoretical papers on the effect in 1961.

Negative resistance oscillations in bulk semiconductors had been observed in the laboratory by J. B. Gunn in 1962, and were thus named the "Gunn effect", but physicist Herbert Kroemer pointed out in 1964 that Gunn's observations could be explained by the RWH theory.In essence, RWH mechanism is the transfer of conduction electrons in a semiconductor from a high mobility valley to lower-mobility, higher-energy satellite valleys. This phenomenon can only be observed in materials that have such energy band structures.

Normally, in a conductor, increasing electric field causes higher charge carrier (usually electron) speeds and results in higher current consistent with Ohm's Law. In a multi-valley semiconductor, though, higher energy may push the carriers into a higher energy state where they actually have higher effective mass and thus slow down. In effect, carrier velocities and current drop as the voltage is increased. While this transfer occurs, the material exhibits a decrease in current – that is, a negative differential resistance. At higher voltages, the normal increase of current with voltage relation resumes once the bulk of the carriers are kicked into the higher energy-mass valley. Therefore the negative resistance only occurs over a limited range of voltages.

Of the type of semiconducting materials satisfying these conditions, gallium arsenide (GaAs) is the most widely understood and used. However RWH mechanisms can also be observed in indium phosphide (InP), cadmium telluride (CdTe), zinc selenide (ZnSe) and indium arsenide (InAs) under hydrostatic or uniaxial pressure.

Sarnoff Corporation

Sarnoff Corporation, with headquarters in West Windsor Township, New Jersey, though with a Princeton address, was a research and development company specializing in vision, video and semiconductor technology. It was named for David Sarnoff, the longtime leader of RCA and NBC.

The cornerstone of Sarnoff Corporation's David Sarnoff Research Center in the Princeton vicinity was laid just before the attack on Pearl Harbor in 1941. That facility, later Sarnoff Corporation headquarters, was the site of several historic developments, including color television, CMOS integrated circuit technology and electron microscopy.

Following 47 years as a central research laboratory for its corporate owner RCA (and briefly for successor GE) as RCA Laboratories, in 1988 the David Sarnoff Research Center was transitioned to Sarnoff Corporation, a wholly owned subsidiary of SRI International. In January 2011, Sarnoff Corporation was integrated into its parent company, SRI International, and continues to engage in similar research and development activities at the Princeton, New Jersey facility. Although located adjacent to Princeton University, the two are not, and have not been, directly affiliated.

UCSB College of Engineering

The College of Engineering (CoE) is one of the three undergraduate colleges at the University of California, Santa Barbara.

As of 2015, there were 150 faculty, 1,450 undergraduate students, and 750 graduate students. According to the Leiden Ranking, engineering and physical sciences at UCSB is ranked #1 among public universities for top 10% research citation impact. According to the National Research Council rankings, the UCSB engineering graduate research program in Materials was ranked #1 and Chemical Engineering ranked #5 in the nation among public universities.

UCSB Physics Department

The Physics Department at the University of California, Santa Barbara has 58 faculty members. It offers academic programs leading to the B.A., B.S., and Ph.D. degrees.

University of California, Santa Barbara

The University of California, Santa Barbara (commonly referred to as UC Santa Barbara or UCSB) is a public research university in Santa Barbara, California. It is one of the 10 campuses of the University of California system. Tracing its roots back to 1891 as an independent teachers' college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system.

UCSB is one of America's Public Ivy universities, a designation that recognizes top public research universities in the U.S. The university is a comprehensive doctoral university, and is organized into five colleges and schools offering 87 undergraduate degrees and 55 graduate degrees. UCSB was ranked 30th among "National Universities", fifth among U.S. public universities, and 37th among Best Global Universities by U.S. News & World Report's 2019 rankings. The university was also ranked 48th worldwide for 2016–17 by the Times Higher Education World University Rankings, and 45th worldwide by the Academic Ranking of World Universities in 2017.UC Santa Barbara is a high-activity research university with 10 national research centers, including the renowned Kavli Institute for Theoretical Physics and the Center for Control, Dynamical-Systems and Computation. Current UCSB faculty includes six Nobel Prize laureates, one Fields Medalist, 39 members of the National Academy of Sciences, 27 members of the National Academy of Engineering, and 34 members of the American Academy of Arts and Sciences. UCSB was the No. 3 host on the ARPAnet and was elected to the Association of American Universities in 1995. The world-class faculty also includes two Academy and Emmy Award winners, and recipients of a Millennium Technology Prize, an IEEE Medal of Honor, a National Medal of Technology and Innovation and a Breakthrough Prize in Fundamental Physics.

The UC Santa Barbara Gauchos compete in the Big West Conference of the NCAA Division I. The Gauchos have won NCAA national championships in men's soccer and men's water polo.

University of Jena

Friedrich Schiller University Jena (FSU; German: Friedrich-Schiller-Universität Jena, shortened form Uni Jena) is a public research university located in Jena, Thuringia, Germany.

The university was established in 1558 and is counted among the ten oldest universities in Germany. It is affiliated with six Nobel Prize winners, most recently in 2000 when Jena graduate Herbert Kroemer won the Nobel Prize for physics. It was renamed after the poet Friedrich Schiller who was teaching as professor of philosophy when Jena attracted some of the most influential minds at the turn of the 19th century. With Karl Leonhard Reinhold, Johann Gottlieb Fichte, G. W. F. Hegel, F. W. J. Schelling and Friedrich von Schlegel on its teaching staff, the university was at the centre of the emergence of German idealism and early Romanticism.

As of 2014, the university has around 19,000 students enrolled and 375 professors. Its current president, Walter Rosenthal, was elected in 2014 for a six-year term.

2000 Nobel Prize laureates
Physiology or Medicine
Economic Sciences

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.