LED Diode:

Introduction:

A semiconductor light source called a light-emitting diode (LED) produces light when current passes through it. Recombining electrons and electron holes in the semiconductor results in the release of energy in the form of photons. The energy needed for electrons to pass through the semiconductor's band gap determines the hue of the light, which corresponds to the energy of the photons. A layer of light-emitting phosphor or several semiconductors can be used to create white light on a semiconductor device.

 

LED Diode

The first LEDs, which debuted as useful electrical components in 1962, released low-intensity infrared (IR) light. Remote-control circuits, such as those used with a variety of consumer gadgets, use infrared LEDs. The early LEDs that produced visible light were dim and only produced red light. Early LEDs were frequently employed in seven-segment displays and as indicator lamps to replace tiny incandescent bulbs.Later innovations led to the creation of LEDs with high, low, or intermediate light output, available in visible, ultraviolet (UV), and infrared wavelengths, such as white LEDs ideal for indoor and outdoor illumination. New kinds of displays and sensors have also been made possible by LEDs, and their quick switching times are advantageous in advanced communications technology. LEDs are also used in a variety of other products, including lighted wallpaper, automotive headlights, advertising, general lighting, traffic signals, traffic lights for horticulture, and medical devices.

 

In comparison to incandescent light sources, LEDs have various benefits, such as lower power consumption, a longer lifespan, increased physical resilience, smaller size, and quicker switching. Despite these largely positive characteristics, LEDs have some drawbacks, such as electrical restrictions to low voltage and typically DC (not AC) power, the inability to provide steady illumination from a pulsing DC or an AC electrical supply source, and lower maximum operating temperature and storage temperature.Unlike LEDs, incandescent lamps can be engineered to run inherently at almost any source voltage. They can also use AC and DC current interchangeably, and they can offer continuous illumination when driven by either, even at frequencies as low as 50 Hz. While an incandescent light bulb can and frequently does work directly from an unregulated DC or AC power source, LEDs typically require electronic support components in order to perform.

 

LEDs function differently from photodiodes in that they convert electricity into light.

 

LED Diode

History:

Using a silicon carbide crystal with a cat's-whisker detector, the English scientist H. J. Round of Marconi Labs first described the phenomena of electroluminescence in 1907. The first LED was reportedly created in 1927, according to Russian inventor Oleg Losev. Although his work was published in Soviet, German, and British scientific publications, the discovery was not used in practice for several decades.

 

When zinc sulphide (ZnS) powder is suspended in an insulator and an alternating electrical field is applied to it, Georges Destriau discovered that electroluminescence can result. Destriau frequently referred to luminescence as Losev-Light in his writings. Destriau was employed by Madame Marie Curie, who conducted radium research and was a forerunner in the science of luminescence.

 

In 1939, the Hungarians Zoltán Bay and György Szigeti filed a patent for a silicon carbide-based lighting system with the option of using boron carbide. This system produced white, yellowish white, or greenish white light depending on the amount of impurities present.

 

LED Diode

These earliest LEDs were described by Kurt Lehovec, Carl Accardo, and Edward Jamgochian in 1951 using a device that used SiC crystals with a battery or pulse generator as the current source and a comparison to a different, pure crystal in 1953.

 

In 1955, Rubin Braunstein of the Radio Corporation of America published a research on the infrared emission of semiconductor alloys such as gallium arsenide (GaAs). At both room temperature and 77 kelvins, Braunstein recorded the infrared emission produced by basic diode structures made of gallium antimonide (GaSb), gadolinium (GaAs), indium phosphide (InP), and silicon-germanium (SiGe) alloys.

 

Further proving that the crude gadgets might be used for non-radio communication over a short distance was Braunstein in 1957. According to Kroemer Braunstein "...had set up a straightforward optical communications link, using appropriate circuitry to modulate a GaAs diode's forward current with music played from a record player. A PbS diode located a long way distant picked up the light that was being released. A loudspeaker played out this signal after it had been fed into an audio amplifier. The music ceased when the beam was intercepted. Playing with this set-up was a lot of fun." This configuration foreshadowed the use of LEDs in optical communication systems.

 

James R. Biard and Gary Pittman, who were employed by Texas Instruments in Dallas, Texas, made the discovery of near-infrared (900 nm) light emission from a tunnel diode they had built on a GaAs substrate in September 1961. By October 1961, they had successfully established signal coupling and effective light emission between a GaAs p-n junction light emitter and a semiconductor photodetector. Based on their discoveries, Biard and Pittman submitted a patent application titled "Semiconductor Radiant Diode" on August 8, 1962. This invention specified a zinc-diffused p-n junction LED with a spaced cathode contact to enable effective infrared light emission under forward bias.

 

The U.S. Patent Office granted the two inventors the patent for the GaAs infrared light-emitting diode (U.S. Patent US3293513), the first practical LED, after determining 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. Texas Instruments (TI) started working on a project to produce infrared diodes as soon as the patent application was submitted. The SNX-100, the first commercial LED device introduced by TI in October 1962, used a pure GaAs crystal to emit light with a 890 nm wavelength. The SNX-110, the first commercially available hemispherical LED, was introduced by TI in October 1963.

 

J. W. Allen and R. J. Cherry presented the first visible-spectrum (red) LED in late 1961 at the SERL in Baldock, United Kingdom. Journal of Physics and Chemistry of Solids, Volume 23, Issue 5, May 1962, pages 509–511 reported on this work. Nick Holonyak presented another early prototype on October 9, 1962, while he was employed by General Electric in Syracuse, New York. On December 1, 1962, Holonyak and Bevacqua published a paper about this LED in the journal Applied Physics Letters. In addition to developing the first yellow LED, M. George Craford, a former graduate student of Holonyak, increased the brightness of red and red-orange LEDs by a factor of ten in 1972. T. P. Pearsall developed novel semiconductor materials that were ideally suited to optical fiber transmission wavelengths in order to create the first high-brightness, high-efficiency LEDs for optical fiber telecommunications in 1976.