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The most common way for LEDs (and diode lasers) to fail is the gradual lowering of light output and loss of efficiency. Sudden failures, however rare, can occur as well. Early red LEDs were notable for their short lifetime.
A diode is a two-terminal electronic component that conducts current primarily in one direction. It has low resistance in one direction and high resistance in the other.
In solid-state physics and solid-state chemistry, a band gap, also called a bandgap or energy gap, is an energy range in a solid where no electronic states exist. In graphs of the electronic band structure of solids, the band gap refers to the energy difference between the top of the valence band and the bottom of the conduction band in insulators and semiconductors. It is the energy required to promote an electron from the valence band to the conduction band. The resulting conduction-band electron are free to move within the crystal lattice and serve as charge carriers to conduct electric current. It is closely related to the HOMO/LUMO gap in chemistry. If the valence band is completely full and the conduction band is completely empty, then electrons cannot move within the solid because there are no available states. If the electrons are not free to move within the crystal lattice, then there is no generated current due to no net charge carrier mobility. However, if some electrons transfer from the valence band to the conduction band, then current can flow. Therefore, the band gap is a major factor determining the electrical conductivity of a solid. Substances having large band gaps are generally insulators, those with small band gaps are semiconductor, and conductors either have very small band gaps or none, because the valence and conduction bands overlap to form a continuous band.
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.
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.
A MESFET is a field-effect transistor semiconductor device similar to a JFET with a Schottky (metal–semiconductor) junction instead of a p–n junction for a gate.
A blue laser emits electromagnetic radiation with a wavelength between 400 and 500 nanometers, which the human eye sees in the visible spectrum as blue or violet.
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 nitride is a semiconductor material made of a mix of gallium nitride (GaN) and indium nitride (InN). It is a ternary group III/group V direct bandgap semiconductor. Its bandgap can be tuned by varying the amount of indium in the alloy. InxGa1−xN has a direct bandgap span from the infrared for InN to the ultraviolet of GaN. The ratio of In/Ga is usually between 0.02/0.98 and 0.3/0.7.
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 spans a direct bandgap ranging from ultraviolet to infrared photon energies.
Current crowding is a nonuniform distribution of current density through a conductor or semiconductor, especially in the vicinity of electrical contacts and over PN junctions.
Thermal laser stimulation represents a class of defect imaging techniques which employ a laser to produce a thermal variation in a semiconductor device. This technique may be used for semiconductor failure analysis. There are four techniques associated with thermal laser stimulation: optical beam induced resistance change (OBIRCH), thermally induced voltage alteration (TIVA)), external induced voltage alteration (XIVA) and Seebeck effect imaging (SEI)
Gallium indium arsenide antimonide phosphide is a semiconductor material.
AlSiC, pronounced "alsick", is a metal matrix composite consisting of aluminium matrix with silicon carbide particles. It has high thermal conductivity, and its thermal expansion can be adjusted to match other materials, e.g. silicon and gallium arsenide chips and various ceramics. It is chiefly used in microelectronics as substrate for power semiconductor devices and high density multi-chip modules, where it aids with removal of waste heat.
Electronic components have a wide range of failure modes. These can be classified in various ways, such as by time or cause. Failures can be caused by excess temperature, excess current or voltage, ionizing radiation, mechanical shock, stress or impact, and many other causes. In semiconductor devices, problems in the device package may cause failures due to contamination, mechanical stress of the device, or open or short circuits.
IQE PLC is a British semiconductor company founded 1988 in Cardiff, Wales, which manufactures advanced epitaxial wafers for a wide range of technology applications for wireless, optoelectronic, electronic and solar devices. IQE specialises in advanced silicon and compound semiconductor materials based on gallium arsenide (GaAs), indium phosphide (InP), gallium nitride (GaN) and silicon. The company is the largest independent outsource producer of epiwafers manufactured by metalorganic vapour phase epitaxy (MOCVD), molecular beam epitaxy (MBE) and chemical vapor deposition (CVD).
Indium arsenide antimonide phosphide is a semiconductor material.
Light-emitting diodes (LEDs) produce light by the recombination of electrons and electron holes in a semiconductor, a process called "electroluminescence". The wavelength of the light produced depends on the energy band gap of the semiconductors used. Since these materials have a high index of refraction, design features of the devices such as special optical coatings and die shape are required to efficiently emit light. A LED is a long-lived light source, but certain mechanisms can cause slow loss of efficiency of the device or sudden failure. The wavelength of the light emitted is a function of the band gap of the semiconductor material used; materials such as gallium arsenide, and others, with various trace doping elements, are used to produce different colors of light. Another type of LED uses a quantum dot which can have its properties and wavelength adjusted by its size. Light-emitting diodes are widely used in indicator and display functions, and white LEDs are displacing other technologies for general illumination purposes.
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.
