Milton Feng co-created the first transistor laser, working with Nick Holonyak in 2004. The paper discussing their work was voted in 2006 as one of the five most important papers published by the American Institute of Physics since its founding 75 years ago. In addition to the invention of transistor laser, he is also well known for inventions of other "major breakthrough" devices, including the world's fastest transistor and light-emitting transistor (LET). As of May, 2009 he is a professor at the University of Illinois at Urbana–Champaign and holds the Nick Holonyak Jr. Endowed Chair Professorship.
In 2003, Milton Feng and his graduate students Walid Hafez and Jie-Wei Lai broke the record for the world's fastest transistor. Their device, made of indium phosphide and indium gallium arsenide with 25 nm thick base and 75 nm thick collector, marked a frequency of 509 GHz, which was 57 GHz faster than the previous record.
In 2005, they succeeded in fabricating a device at Micro and Nanotechnology Laboratory to break their own record, reaching 604 GHz.
In 2006, Feng and his other graduate student William Snodgrass fabricated an indium phosphide and indium gallium arsenide device with 12.5 nm thick base, operating at 765 GHz at room temperature and 845 GHz at -55 °C. [2] [3]
Reported in the January 5 issue of the journal Applied Physics Letters in 2004, Milton Feng and Nick Holonyak, the inventor of the first practical light-emitting diode (LED) and the first semiconductor laser to operate in the visible spectrum, made the world's first light-emitting transistor. This hybrid device, fabricated by Feng's graduate student Walid Hafez, had one electrical input and two outputs (electrical output and optical output) and operated at a frequency of 1 MHz. The device was made of indium gallium phosphide, indium gallium arsenide, and gallium arsenide, and emitted infrared photons from the base layer. [4] [5]
Described in the November 15 issue of the journal Applied Physics Letters in 2004, Milton Feng, Nick Holonyak, postdoctoral research associate Gabriel Walter, and graduate research assistant Richard Chan demonstrated operation of the first heterojunction bipolar transistor laser by incorporating a quantum well in the active region of a light-emitting transistor. As with a light-emitting transistor, the transistor laser was made of indium gallium phosphide, indium gallium arsenide, and gallium arsenide, but emitted a coherent beam by stimulated emission, which differed from their previous device that only emitted incoherent photons. Despite their success, the device was not useful for practical purposes since it only operated at low temperatures – about minus 75 Celsius degrees.
Within a year, though, the researchers finally fabricated a transistor laser operating at room temperature by using metal organic chemical vapor deposition (MOCVD), as reported in the September 26 issue of the same journal. At this time, the transistor laser had a 14-layer structure including aluminium gallium arsenide optical confining layers and indium gallium arsenide quantum wells. The emitting cavity was 2,200 nm wide and 0.85 mm long, and had continuous modes at 1,000 nm. In addition, it had a threshold current of 40 mA and direct modulation of the laser at 3 GHz.
A laser diode is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with electrical current can create lasing conditions at the diode's junction.
Gallium arsenide (GaAs) is a III-V direct band gap semiconductor with a zinc blende crystal structure.
Nick Holonyak Jr. was an American engineer and educator. He is noted particularly for his 1962 invention and first demonstration of a semiconductor laser diode that emitted visible light. This device was the forerunner of the first generation of commercial light-emitting diodes (LEDs). He was then working at a General Electric research laboratory near Syracuse, New York. He left General Electric in 1963 and returned to his alma mater, the University of Illinois at Urbana-Champaign, where he later became John Bardeen Endowed Chair in Electrical and Computer Engineering and Physics.
Monolithic microwave integrated circuit, or MMIC, is a type of integrated circuit (IC) device that operates at microwave frequencies. These devices typically perform functions such as microwave mixing, power amplification, low-noise amplification, and high-frequency switching. Inputs and outputs on MMIC devices are frequently matched to a characteristic impedance of 50 ohms. This makes them easier to use, as cascading of MMICs does not then require an external matching network. Additionally, most microwave test equipment is designed to operate in a 50-ohm environment.
Indium phosphide (InP) is a binary semiconductor composed of indium and phosphorus. It has a face-centered cubic ("zincblende") crystal structure, identical to that of GaAs and most of the III-V semiconductors.
SiGe, or silicon–germanium, is an alloy with any molar ratio of silicon and germanium, i.e. with a molecular formula of the form Si1−xGex. It is commonly used as a semiconductor material in integrated circuits (ICs) for heterojunction bipolar transistors or as a strain-inducing layer for CMOS transistors. IBM introduced the technology into mainstream manufacturing in 1989. This relatively new technology offers opportunities in mixed-signal circuit and analog circuit IC design and manufacture. SiGe is also used as a thermoelectric material for high-temperature applications (>700 K).
A heterojunction bipolar transistor (HBT) is a type of bipolar junction transistor (BJT) that uses different 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.
Indium gallium phosphide (InGaP), also called gallium indium phosphide (GaInP), is a semiconductor composed of indium, gallium and phosphorus. It is used in high-power and high-frequency electronics because of its superior electron velocity with respect to the more common semiconductors silicon and gallium arsenide.
Indium gallium arsenide (InGaAs) is a ternary alloy of indium arsenide (InAs) and gallium arsenide (GaAs). Indium and gallium are group III elements of the periodic table while arsenic is a group V element. Alloys made of these chemical groups are referred to as "III-V" compounds. InGaAs has properties intermediate between those of GaAs and InAs. InGaAs is a room-temperature semiconductor with applications in electronics and photonics.
Indium arsenide, InAs, or indium monoarsenide, is a narrow-bandgap semiconductor composed of indium and arsenic. It has the appearance of grey cubic crystals with a melting point of 942 °C.
Aluminium gallium indium phosphide is a semiconductor material that provides a platform for the development of multi-junction photovoltaics and optoelectronic devices. It has a direct bandgap ranging from ultraviolet to infrared photon energies.
Gallium arsenide phosphide is a semiconductor material, an alloy of gallium arsenide and gallium phosphide. It exists in various composition ratios indicated in its formula by the fraction x.
A hybrid silicon laser is a semiconductor laser fabricated from both silicon and group III-V semiconductor materials. The hybrid silicon laser was developed to address the lack of a silicon laser to enable fabrication of low-cost, mass-producible silicon optical devices. The hybrid approach takes advantage of the light-emitting properties of III-V semiconductor materials combined with the process maturity of silicon to fabricate electrically driven lasers on a silicon wafer that can be integrated with other silicon photonic devices.
A quantum-well laser is a laser diode in which the active region of the device is so narrow that quantum confinement occurs. Laser diodes are formed in compound semiconductor materials that are able to emit light efficiently. The wavelength of the light emitted by a quantum-well laser is determined by the width of the active region rather than just the bandgap of the materials from which it is constructed. This means that much shorter wavelengths can be obtained from quantum-well lasers than from conventional laser diodes using a particular semiconductor material. The efficiency of a quantum-well laser is also greater than a conventional laser diode due to the stepwise form of its density of states function.
Gallium indium arsenide antimonide phosphide is a semiconductor material.
IQE PLC is a British semiconductor company founded 1988 in Cardiff, Wales, which manufactures advanced epitaxial wafers.
Indium arsenide antimonide phosphide is a semiconductor material.
Transistor laser is a semiconductor device that functions as a transistor with an electrical output and an optical output, as opposed to the typical two electrical outputs. This optical output separates it from typical transistors and, because optical signals travel faster than electrical signals, has the potential to speed up computing immensely. Researchers who discovered the transistor laser developed a new model of Kirchhoff's current law to better model the behavior of simultaneous optical and electrical output.
A light-emitting transistor or LET is a form of transistor that emits light. Higher efficiency than light-emitting diode (LED) is possible.
James J. Coleman is an electrical engineer who worked at Bell Labs, Rockwell International, and the University of Illinois, Urbana. He is best known for his work on semiconductor lasers, materials and devices including strained-layer indium gallium arsenide lasers and selective area epitaxy. Coleman is a Fellow of the IEEE and a member of the US National Academy of Engineering.