Rubin J. Braunstein
|Born||May 6, 1922|
New York, USA
|Died||June 9, 2018 (aged 96)|
|Education||Syracuse University, Ph.D. (1954)|
|Fields||semiconductor physics, optics|
|Institutions||RCA Laboratory, UCLA|
|Doctoral advisor||John Trischka|
Rubin Braunstein (1922–2018) was an American physicist and educator. In 1955 he published the first measurements of light emission by semiconductor diodes made from crystals of gallium arsenide (GaAs), gallium antimonide (GaSb), and indium phosphide (InP). GaAs, GaSb, and InP are examples of III-V semiconductors. The III-V semiconductors absorb and emit light much more strongly than silicon, which is the best-known semiconductor. Braunstein's devices are the forerunners of contemporary LED lighting and semiconductor lasers, which typically employ III-V semiconductors. The 2000 and 2014 Nobel Prizes in Physics were awarded for further advances in closely related fields.
Braunstein was raised in New York City. He earned a doctorate in physics from Syracuse University in 1954. He then joined the research laboratory of the RCA Corporation, which was among the most active industrial laboratories at the time. In the following decade at RCA Laboratories he published broadly on semiconductor physics and technology. Beyond his seminal work with light emission from III-V semiconductors, in 1964 he exploited newly invented lasers to publish the first paper on two-photon absorption in semiconductors. Typically, only individual photons (particles of light) with some minimum energy are absorbed by a given semiconductor. For very high intensity beams of light, two photons, each with half that minimum energy, can be absorbed simultaneously. He also published highly cited foundation papers on the electronic, optical, and vibrational properties of III-V semiconductors, silicon, and germanium.
In 1964 Braunstein became a professor of physics at University of California, Los Angeles (UCLA), where he remained for the rest of his career. His research there continued his RCA work with optoelectronic properties of semiconductors as well as contributions related to the optical properties of highly transparent materials such as tungstate glasses. Some of Braunstein's work was theoretical, including the proposal that neutral atoms could be scattered by a sufficiently intense standing wave of light. Since light is an electromagnetic wave, it had long been known that charged particles like electrons would be scattered. The effect with neutral atoms is much weaker, but was finally observed nearly 20 years after the proposal of Braunstein and his co-authors.
- "Rubin Braunstein". Dignity Memorial. June 12, 2018.
- "Rubin Braunstein". UCLA.
- Schubert, E. Fred (2003). Light-Emitting Diodes. Cambridge University Press. p. 2. ISBN 9780986382666.
The advent of infrared (IR) LEDs made from III-V semiconductors dates back to 1955 when Braunstein (1955) reported the first electroluminescence from n-type GaAs and n-type GaSb. Braunstein's LEDs were inefficient, not based on a pn junction, and instead based on a rectifying metal-semiconductor contact (Schottky contact).
- Khan, M. Nisa (2013). Understanding LED Illumination. CRC Press. p. 29. ISBN 9781466507739.
Braunstein reported on the observation of infrared emission from simple diodes constructed from gallium arsenide (GaAs), gallium antimonide (GaSb), and gallium phosphide (GaP) at room temperature and at 77 K. The first infrared LED patent, however, was awarded in 1961 to Robert Biard and Gary Pittman from Texas Instruments ...
- Hecht, Jeff (July 2007). "The Breakthrough Birth of the Diode Laser". Optics & Photonics News.
In 1955, Rubin Braunstein was the first to observe emission from gallium arsenide and two other III-V compounds—indium phosphide and gallium antimonide—at RCA Laboratories in Princeton, N.J.. His LEDs were Schottky diodes formed by point contacts or silver paint; junction diodes were not available. He worked at liquid nitrogen temperature, where much less of the recombination energy is lost to nonradiative processes than at room temperature, and observed peak emission close to the band gaps of the compounds, confirming that the light was recombination radiation. His LEDs emitted enough infrared light to play music from a phonograph record, but the light wasn’t visible, and scientists’ interest in GaAs remained mainly focused on fast electronic devices.
- Gross, Benjamin (October 9, 2014). "How America Lighted the Way for a Japanese Nobel". The Wall Street Journal.
- Vaidyanathan, A.; Walker, T.; Guenther, A. H.; Mitra, S. S.; Narducci, L. M. (15 January 1980). "Two-photon absorption in several direct-gap crystals". Phys. Rev. B. 21 (2): 743. Bibcode:1980PhRvB..21..743V. doi:10.1103/PhysRevB.21.743.
- von Klingshirn, Claus (2007). Semiconductor Optics (3 ed.). Springer. p. 473. ISBN 9783540383475.
- Seeger, Karlheinz (1982). Semiconductor Physics: An Introduction (2 ed.). Springer. ISBN 9783662023518. OCLC 1086541248. Several papers by Braunstein and his colleagues are used as original references.
- "Rubin Braunstein". UCLA. Archived from the original on March 11, 2011.
- Gould, Phillip L.; Ruff, George A.; Pritchard, David E. (February 24, 1986). "Diffraction of Atoms by Light: The Near-Resonant Kapitza-Dirac Effect". Physical Review Letters. 56 (8): 827–830. Bibcode:1986PhRvL..56..827G. doi:10.1103/PhysRevLett.56.827. PMID 10033296.
- "APS Fellow Archive". American Physical Society. Retrieved 2019-04-03.
- Braunstein, Rubin (1955). "Radiative Transitions in Semiconductors". Physical Review. 99 (6): 1892–1893. Bibcode:1955PhRv...99.1892B. doi:10.1103/PhysRev.99.1892.
- Braunstein, R.; Ockman, N. (20 April 1964). "Optical Double-Photon Absorption in CdS". Physical Review. 134 (2A): A499. Bibcode:1964PhRv..134..499B. doi:10.1103/PhysRev.134.A499.
- on YouTube. Family video.
- Herbert Kroemer, whose office at RCA adjoined Braunstein's and who later won the Nobel Prize in Physics, has told an anecdote about Braunstein's early use of an infrared emitting GaAs diode to transmit information. See Kroemer, Herbert (Sep 16, 2013). "The Double-Heterostructure Concept: How It Got Started". Proceedings of the IEEE. 101 (10): 2183–2187. doi:10.1109/JPROC.2013.2274914.
Braunstein had set up a simple optical communications link: Music emerging from a record player was used via suitable electronics to modulate the forward current of a GaAs diode. The emitted light was detected by a PbS diode some distance away. This signal was fed into an audio amplifier and played back by a loudspeaker. Intercepting the beam stopped the music. We had a great deal of fun playing with this setup.
- Pascoe, Sue (November 19, 2014). "Palisadian Rubin Braunstein's LED Discovery Cited". Palisades News.