praj-17/QA-MCQ-Open-ended huggingface dataset:
Title: Light-emitting_diode
Context: In 1957, Braunstein further demonstrated that the rudimentary devices could be used for non-radio communication across a short distance. As noted by Kroemer 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." This setup presaged the use of LEDs for optical communication applications.

question: What year was it discovered that early LED instruments could be used for non-radio communication? 

answer: 1957

question: Who discovered non-radio uses for early LED devices? 

answer: Kroemer Braunstein

question: The current in non-radio communication had to go through what type of component? 

answer: a GaAs diode

question: What other component was needed to detect the first current of a non-radio signal? 

answer: a PbS diode

question: What final device was needed to hear the signal from the initial GaAs diode? 

answer: audio amplifier
Title: Light-emitting_diode
Context: In September 1961, while working at Texas Instruments in Dallas, Texas, James R. Biard and Gary Pittman discovered near-infrared (900 nm) light emission from a tunnel diode they had constructed on a GaAs substrate. By October 1961, they had demonstrated efficient light emission and signal coupling between a GaAs p-n junction light emitter and an electrically-isolated semiconductor photodetector. On August 8, 1962, Biard and Pittman filed a patent titled "Semiconductor Radiant Diode" based on their findings, which described a zinc diffused p–n junction LED with a spaced cathode contact to allow for efficient emission of infrared light under forward bias. After establishing the priority of their work based on engineering notebooks predating submissions from G.E. Labs, RCA Research Labs, IBM Research Labs, Bell Labs, and Lincoln Lab at MIT, the U.S. patent office issued the two inventors the patent for the GaAs infrared (IR) light-emitting diode (U.S. Patent US3293513), the first practical LED. Immediately after filing the patent, Texas Instruments (TI) began a project to manufacture infrared diodes. In October 1962, TI announced the first LED commercial product (the SNX-100), which employed a pure GaAs crystal to emit a 890 nm light output. In October 1963, TI announced the first commercial hemispherical LED, the SNX-110.

question: In what state what near-infrared light emission discovered?  

answer: Texas

question: What type of diode was used to help discover near-infrared light emission? 

answer: tunnel

question: In what year was the patent filed for the Semiconductor Radiant Diode? 

answer: 1962

question: What was the first practical LED? 

answer: GaAs infrared (IR) light-emitting diode

question: The two inventors of the first practical diode were employed by what famous company? 

answer: Texas Instruments (TI)
Title: Light-emitting_diode
Context: The first visible-spectrum (red) LED was developed in 1962 by Nick Holonyak, Jr., while working at General Electric Company. Holonyak first reported his LED in the journal Applied Physics Letters on the December 1, 1962. M. George Craford, a former graduate student of Holonyak, invented the first yellow LED and improved the brightness of red and red-orange LEDs by a factor of ten in 1972. In 1976, T. P. Pearsall created the first high-brightness, high-efficiency LEDs for optical fiber telecommunications by inventing new semiconductor materials specifically adapted to optical fiber transmission wavelengths.

question: At what global company was the first visible-spectrum LED developed? 

answer: General Electric Company

question: What GE employee developed the visible-spectrum LED? 

answer: Nick Holonyak, Jr.

question: What color is associated with the visible-spectrum LED? 

answer: red

question: What color LED was later created in 1972? 

answer: yellow

question: What graduate student of Holonyak created the yellow LED? 

answer: M. George Craford
Title: Light-emitting_diode
Context: The first commercial LEDs were commonly used as replacements for incandescent and neon indicator lamps, and in seven-segment displays, first in expensive equipment such as laboratory and electronics test equipment, then later in such appliances as TVs, radios, telephones, calculators, as well as watches (see list of signal uses). Until 1968, visible and infrared LEDs were extremely costly, in the order of US$200 per unit, and so had little practical use. The Monsanto Company was the first organization to mass-produce visible LEDs, using gallium arsenide phosphide (GaAsP) in 1968 to produce red LEDs suitable for indicators. Hewlett Packard (HP) introduced LEDs in 1968, initially using GaAsP supplied by Monsanto. These red LEDs were bright enough only for use as indicators, as the light output was not enough to illuminate an area. Readouts in calculators were so small that plastic lenses were built over each digit to make them legible. Later, other colors became widely available and appeared in appliances and equipment. In the 1970s commercially successful LED devices at less than five cents each were produced by Fairchild Optoelectronics. These devices employed compound semiconductor chips fabricated with the planar process invented by Dr. Jean Hoerni at Fairchild Semiconductor. The combination of planar processing for chip fabrication and innovative packaging methods enabled the team at Fairchild led by optoelectronics pioneer Thomas Brandt to achieve the needed cost reductions. These methods continue to be used by LED producers.

question: What was the first commercial uses of LEDs? 

answer: replacements for incandescent and neon indicator lamps

question: How much did the early LEDs cost? 

answer: US$200 per unit

question: What was one use of early LED light in products? 

answer: calculators

question: What modern company introduced LEDs in 1968? 

answer: Hewlett Packard (HP)

question: In what decade were production costs greatly reduced for LEDs to enable successful commercial uses? 

answer: 1970s
Title: Light-emitting_diode
Context: The first high-brightness blue LED was demonstrated by Shuji Nakamura of Nichia Corporation in 1994 and was based on InGaN. In parallel, Isamu Akasaki and Hiroshi Amano in Nagoya were working on developing the important GaN nucleation on sapphire substrates and the demonstration of p-type doping of GaN. Nakamura, Akasaki and Amano were awarded the 2014 Nobel prize in physics for their work. In 1995, Alberto Barbieri at the Cardiff University Laboratory (GB) investigated the efficiency and reliability of high-brightness LEDs and demonstrated a "transparent contact" LED using indium tin oxide (ITO) on (AlGaInP/GaAs).

question: What color LED was demonstrated in 1994? 

answer: blue

question: Who demonstrated the first blue LED? 

answer: Shuji Nakamura

question: What did Nakamura, Akasaki, and Amano receive for their work? 

answer: 2014 Nobel prize in physics

question: Who investigated the efficiency of high-brightness LED at Cardiff University in 1995? 

answer: Alberto Barbieri

question: What substance did Barbieri use in his work with high-brightness LED? 

answer: indium tin oxide
Title: Light-emitting_diode
Context: The attainment of high efficiency in blue LEDs was quickly followed by the development of the first white LED. In this device a Y
3Al
5O
12:Ce (known as "YAG") phosphor coating on the emitter absorbs some of the blue emission and produces yellow light through fluorescence. The combination of that yellow with remaining blue light appears white to the eye. However using different phosphors (fluorescent materials) it also became possible to instead produce green and red light through fluorescence. The resulting mixture of red, green and blue is not only perceived by humans as white light but is superior for illumination in terms of color rendering, whereas one cannot appreciate the color of red or green objects illuminated only by the yellow (and remaining blue) wavelengths from the YAG phosphor.

question: What LED quickly followed the blue LEDs? 

answer: white

question: What does the YAG phosphor coating produce? 

answer: yellow light
Title: Light-emitting_diode
Context: A P-N junction can convert absorbed light energy into a proportional electric current. The same process is reversed here (i.e. the P-N junction emits light when electrical energy is applied to it). This phenomenon is generally called electroluminescence, which can be defined as the emission of light from a semi-conductor under the influence of an electric field. The charge carriers recombine in a forward-biased P-N junction as the electrons cross from the N-region and recombine with the holes existing in the P-region. Free electrons are in the conduction band of energy levels, while holes are in the valence energy band. Thus the energy level of the holes will be lesser than the energy levels of the electrons. Some portion of the energy must be dissipated in order to recombine the electrons and the holes. This energy is emitted in the form of heat and light.

question: What converts absorbed light energy into an electric current? 

answer: P-N junction

question: What is the phenomenon where a P-N junction emits light when an electrical current is applied to it? 

answer: electroluminescence

question: Where are the free electrons located in the production of electroluminescence? 

answer: the conduction band

question: Whose energy levels are lower than the electrons in the electroluminescence process? 

answer: holes existing in the P-region

question: Why is some energy in the electroluminescence process emitted as heat and light? 

answer: to recombine the electrons and the holes
Title: Light-emitting_diode
Context: In September 2003, a new type of blue LED was demonstrated by Cree that consumes 24 mW at 20 milliamperes (mA). This produced a commercially packaged white light giving 65 lm/W at 20 mA, becoming the brightest white LED commercially available at the time, and more than four times as efficient as standard incandescents. In 2006, they demonstrated a prototype with a record white LED luminous efficacy of 131 lm/W at 20 mA. Nichia Corporation has developed a white LED with luminous efficacy of 150 lm/W at a forward current of 20 mA. Cree's XLamp XM-L LEDs, commercially available in 2011, produce 100 lm/W at their full power of 10 W, and up to 160 lm/W at around 2 W input power. In 2012, Cree announced a white LED giving 254 lm/W, and 303 lm/W in March 2014. Practical general lighting needs high-power LEDs, of one watt or more. Typical operating currents for such devices begin at 350 mA.

question: In what year was a new type of blue LED produced? 

answer: 2003

question: Who demonstrated in 2003 the new type of blue LED? 

answer: Cree

question: How much more efficient as standard incandescents was the white LED commercially available in 2003? 

answer: four times

question: What is the typical operating current for high-power LEDs? 

answer: 350 mA
Title: Light-emitting_diode
Context: The most common symptom of LED (and diode laser) failure is the gradual lowering of light output and loss of efficiency. Sudden failures, although rare, can also occur. Early red LEDs were notable for their short service life. With the development of high-power LEDs the devices are subjected to higher junction temperatures and higher current densities than traditional devices. This causes stress on the material and may cause early light-output degradation. To quantitatively classify useful lifetime in a standardized manner it has been suggested to use L70 or L50, which are the runtimes (typically given in thousands of hours) at which a given LED reaches 70% and 50% of initial light output, respectively.

question: What is a symptom of LED failure? 

answer: loss of efficiency

question: What is rare in LED lighting? 

answer: Sudden failures

question: What was notable in early red LEDs? 

answer: their short service life

question: What could cause early light-output degradation in LEDs? 

answer: higher junction temperatures

question: What is a classification used in LED lighting to describe how much usefulness it will receive? 

answer: L70 or L50
Title: Light-emitting_diode
Context: Since LED efficacy is inversely proportional to operating temperature, LED technology is well suited for supermarket freezer lighting. Because LEDs produce less waste heat than incandescent lamps, their use in freezers can save on refrigeration costs as well. However, they may be more susceptible to frost and snow buildup than incandescent lamps, so some LED lighting systems have been designed with an added heating circuit. Additionally, research has developed heat sink technologies that will transfer heat produced within the junction to appropriate areas of the light fixture.

question: LED efficacy is inversely proportional to what? 

answer: operating temperature

question: Where is LED lighting very well suited? 

answer: supermarket freezer

question: LEDs produce less waste heat than what other device? 

answer: incandescent lamps

question: What is LED lighting more susceptible to than incandescent light? 

answer: frost
Title: Light-emitting_diode
Context: The first blue-violet LED using magnesium-doped gallium nitride was made at Stanford University in 1972 by Herb Maruska and Wally Rhines, doctoral students in materials science and engineering. At the time Maruska was on leave from RCA Laboratories, where he collaborated with Jacques Pankove on related work. In 1971, the year after Maruska left for Stanford, his RCA colleagues Pankove and Ed Miller demonstrated the first blue electroluminescence from zinc-doped gallium nitride, though the subsequent device Pankove and Miller built, the first actual gallium nitride light-emitting diode, emitted green light. In 1974 the U.S. Patent Office awarded Maruska, Rhines and Stanford professor David Stevenson a patent for their work in 1972 (U.S. Patent US3819974 A) and today magnesium-doping of gallium nitride continues to be the basis for all commercial blue LEDs and laser diodes. These devices built in the early 1970s had too little light output to be of practical use and research into gallium nitride devices slowed. In August 1989, Cree introduced the first commercially available blue LED based on the indirect bandgap semiconductor, silicon carbide (SiC). SiC LEDs had very low efficiency, no more than about 0.03%, but did emit in the blue portion of the visible light spectrum.[citation needed]

question: What students developed the first blue-violet LED? 

answer: Herb Maruska and Wally Rhines

question: The first blue-violet LED was developed at what University? 

answer: Stanford

question: When was the first blue-violet LED developed? 

answer: 1972

question: What substance helped demonstrate the first blue electroluminescence? 

answer: zinc-doped gallium nitride
Title: Light-emitting_diode
Context: In the late 1980s, key breakthroughs in GaN epitaxial growth and p-type doping ushered in the modern era of GaN-based optoelectronic devices. Building upon this foundation, Dr. Moustakas at Boston University patented a method for producing high-brightness blue LEDs using a new two-step process. Two years later, in 1993, high-brightness blue LEDs were demonstrated again by Shuji Nakamura of Nichia Corporation using a gallium nitride growth process similar to Dr. Moustakas's. Both Dr. Moustakas and Mr. Nakamura were issued separate patents, which confused the issue of who was the original inventor (partly because although Dr. Moustakas invented his first, Dr. Nakamura filed first).[citation needed] This new development revolutionized LED lighting, making high-power blue light sources practical, leading to the development of technologies like BlueRay, as well as allowing the bright high resolution screens of modern tablets and phones.[citation needed]

question: In what decade were breakthroughs made that brought in the modern era of GaN-based optoelectronic devices? 

answer: 1980s

question: Who first patented a method to produce high-brightness blue LEDs? 

answer: Shuji Nakamura

question: Who first invented a method to produce high-brightness blue LEDs? 

answer: Dr. Moustakas

question: What technology was made possible by high-power blue light sources? 

answer: BlueRay

question: What is one modern gadget that benefits from high-power blue LED lighting? 

answer: tablets
Title: Light-emitting_diode
Context: Nakamura was awarded the 2006 Millennium Technology Prize for his invention. Nakamura, Hiroshi Amano and Isamu Akasaki were awarded the Nobel Prize in Physics in 2014 for the invention of the blue LED. In 2015, a US court ruled that three companies (i.e. the litigants who had not previously settled out of court) that had licensed Mr. Nakamura's patents for production in the United States had infringed Dr. Moustakas's prior patent, and order them to pay licensing fees of not less than 13 million USD.

question: What Nobel Prize did Nakamura, Amano, and Akasaki receive in 2014? 

answer: Physics

question: What award did Nakamura receive in 2006 for his invention? 

answer: Millennium Technology Prize

question: How many companies did a judge say infringed on Dr. Moustakas's prior blue light patent in 2015? 

answer: three

question: What was the fine given to the three companies? 

answer: not less than 13 million USD
Title: Light-emitting_diode
Context: By the late 1990s, blue LEDs became widely available. They have an active region consisting of one or more InGaN quantum wells sandwiched between thicker layers of GaN, called cladding layers. By varying the relative In/Ga fraction in the InGaN quantum wells, the light emission can in theory be varied from violet to amber. Aluminium gallium nitride (AlGaN) of varying Al/Ga fraction can be used to manufacture the cladding and quantum well layers for ultraviolet LEDs, but these devices have not yet reached the level of efficiency and technological maturity of InGaN/GaN blue/green devices. If un-alloyed GaN is used in this case to form the active quantum well layers, the device will emit near-ultraviolet light with a peak wavelength centred around 365 nm. Green LEDs manufactured from the InGaN/GaN system are far more efficient and brighter than green LEDs produced with non-nitride material systems, but practical devices still exhibit efficiency too low for high-brightness applications.[citation needed]

question: What are cladding layers? 

answer: active region consisting of one or more InGaN quantum wells sandwiched between thicker layers of GaN

question: How can light emission be varied from violet to amber? 

answer: By varying the relative In/Ga fraction in the InGaN quantum wells

question: What does AlGaN stand for? 

answer: Aluminium gallium nitride

question: What LEDs are more efficient when produced from the InGaN/GaN systems than without? 

answer: Green
Title: Light-emitting_diode
Context: With nitrides containing aluminium, most often AlGaN and AlGaInN, even shorter wavelengths are achievable. Ultraviolet LEDs in a range of wavelengths are becoming available on the market. Near-UV emitters at wavelengths around 375–395 nm are already cheap and often encountered, for example, as black light lamp replacements for inspection of anti-counterfeiting UV watermarks in some documents and paper currencies. Shorter-wavelength diodes, while substantially more expensive, are commercially available for wavelengths down to 240 nm. As the photosensitivity of microorganisms approximately matches the absorption spectrum of DNA, with a peak at about 260 nm, UV LED emitting at 250–270 nm are to be expected in prospective disinfection and sterilization devices. Recent research has shown that commercially available UVA LEDs (365 nm) are already effective disinfection and sterilization devices. UV-C wavelengths were obtained in laboratories using aluminium nitride (210 nm), boron nitride (215 nm) and diamond (235 nm).

question: What substance does nitrides contain? 

answer: aluminium

question: What sort of LEDs are becoming more available on the market? 

answer: Ultraviolet

question: What is the range of wavelengths for cheap UV LEDs? 

answer: 375–395 nm

question: Shorter wavelength diodes provide wavelengths as low as what? 

answer: 240 nm

question: What UV wavelengths are found in sterilization devices? 

answer: 250–270 nm
Title: Light-emitting_diode
Context: White light can be formed by mixing differently colored lights; the most common method is to use red, green, and blue (RGB). Hence the method is called multi-color white LEDs (sometimes referred to as RGB LEDs). Because these need electronic circuits to control the blending and diffusion of different colors, and because the individual color LEDs typically have slightly different emission patterns (leading to variation of the color depending on direction) even if they are made as a single unit, these are seldom used to produce white lighting. Nonetheless, this method has many applications because of the flexibility of mixing different colors, and in principle, this mechanism also has higher quantum efficiency in producing white light.[citation needed]

question: What colors are used to form white light? 

answer: red, green, and blue

question: What is the method called that mixes red, green, and blue colors to form white light? 

answer: multi-color white LEDs

question: What does the multi-color white LED method need to produce the end result? 

answer: electronic circuits

question: What is another name to reference the multi-color white LED method? 

answer: RGB LEDs
Title: Light-emitting_diode
Context: There are several types of multi-color white LEDs: di-, tri-, and tetrachromatic white LEDs. Several key factors that play among these different methods, include color stability, color rendering capability, and luminous efficacy. Often, higher efficiency will mean lower color rendering, presenting a trade-off between the luminous efficacy and color rendering. For example, the dichromatic white LEDs have the best luminous efficacy (120 lm/W), but the lowest color rendering capability. However, although tetrachromatic white LEDs have excellent color rendering capability, they often have poor luminous efficacy. Trichromatic white LEDs are in between, having both good luminous efficacy (>70 lm/W) and fair color rendering capability.

question: What is a factor that may be different in the various types of multi-color white LEDs? 

answer: luminous efficacy

question: Higher efficiency in multi-color white LEDs may mean what? 

answer: lower color rendering

question: What is one type of multi-color white LED? 

answer: tetrachromatic

question: What type has the best luminous efficacy? 

answer: dichromatic white LEDs

question: What luminous efficacy does trichromatic white LEDs have? 

answer: >70 lm/W