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Photodiode
A photodiode is a light-sensitive semiconductor diode. It produces current when it absorbs photons. The package of a photodiode allows light (or infrared or ultraviolet radiation, or X-rays) to reach the sensitive part of the device. The package may include lenses or optical filters. Devices designed for use specially as a photodiode use a PIN junction rather than a p–n junction, to increase the speed of response. Photodiodes usually have a slower response time as their surface area increases. A photodiode is designed to operate in reverse bias. A solar cell used to generate electric solar power is a large area photodiode. Photodiodes are used in scientific and industrial instruments to measure light intensity, either for its own sake or as a measure of some other property (density of smoke, for example). A photodiode can be used as the receiver of data encoded on an infrared beam, as in household remote controls. Photodiodes can be used to form an optocoupler, allowing tra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photodiode Operation
A photodiode is a light-sensitive semiconductor diode. It produces current when it absorbs photons. The package of a photodiode allows light (or infrared or ultraviolet radiation, or X-rays) to reach the sensitive part of the device. The package may include lenses or optical filters. Devices designed for use specially as a photodiode use a PIN junction rather than a p–n junction, to increase the speed of response. Photodiodes usually have a slower response time as their surface area increases. A photodiode is designed to operate in reverse bias. A solar cell used to generate electric solar power is a large area photodiode. Photodiodes are used in scientific and industrial instruments to measure light intensity, either for its own sake or as a measure of some other property (density of smoke, for example). A photodiode can be used as the receiver of data encoded on an infrared beam, as in household remote controls. Photodiodes can be used to form an optocoupler, allowing tra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avalanche Photodiode
An avalanche photodiode (APD) is a highly sensitive semiconductor photodiode detector that exploits the photoelectric effect to convert light into electricity. From a functional standpoint, they can be regarded as the semiconductor analog of photomultiplier tubes. The avalanche photodiode (APD) was invented by Japanese engineer Jun-ichi Nishizawa in 1952. However, study of avalanche breakdown, microplasma defects in silicon and germanium and the investigation of optical detection using p-n junctions predate this patent. Typical applications for APDs are laser rangefinders, long-range fiber-optic telecommunication, and quantum sensing for control algorithms. New applications include positron emission tomography and particle physics. It was discovered in 2020 that adding graphene layer can prevent degradation over time to keep avalanche photodiode''like new'' which is important in shrinking their size and costs for many diverse applications & bringing devices out of vacuum tubes in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diode
A diode is a two-terminal electronic component that conducts current primarily in one direction (asymmetric conductance); it has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other. A diode vacuum tube or thermionic diode is a vacuum tube with two electrodes, a heated cathode and a plate, in which electrons can flow in only one direction, from cathode to plate. A semiconductor diode, the most commonly used type today, is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals. Semiconductor diodes were the first semiconductor electronic devices. The discovery of asymmetric electrical conduction across the contact between a crystalline mineral and a metal was made by German physicist Ferdinand Braun in 1874. Today, most diodes are made of silicon, but other semiconducting materials such as gallium arsenide and germanium are also used. Among many uses, diodes are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photovoltaic Effect
The photovoltaic effect is the generation of voltage and electric current in a material upon exposure to light. It is a physical and chemical phenomenon. The photovoltaic effect is closely related to the photoelectric effect. For both phenomena, light is absorbed, causing excitation of an electron or other charge carrier to a higher-energy state. The main distinction is that the term ''photoelectric effect'' is now usually used when the electron is ejected out of the material (usually into a vacuum) and ''photovoltaic effect'' used when the excited charge carrier is still contained within the material. In either case, an electric potential (or voltage) is produced by the separation of charges, and the light has to have a sufficient energy to overcome the potential barrier for excitation. The physical essence of the difference is usually that photoelectric emission separates the charges by ballistic conduction and photovoltaic emission separates them by diffusion, but some "hot car ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photocurrent
Photocurrent is the electric current through a photosensitive device, such as a photodiode, as the result of exposure to radiant power. The photocurrent may occur as a result of the photoelectric, photoemissive, or photovoltaic effect. The photocurrent may be enhanced by internal gain caused by interaction among ions and photons under the influence of applied fields, such as occurs in an avalanche photodiode (APD). When a suitable radiation is used, the photoelectric current is directly proportional to intensity of radiation and increases with the increase in accelerating potential till the stage is reached when photo-current becomes maximum and does not increase with further increase in accelerating potential. The highest (maximum) value of the photo-current is called saturation current. The value of retarding potential at which photo-current becomes zero is called cut-off voltage or stopping potential for the given frequency of the incident ray. Photovoltaics The generation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shive Wave Machine
John Northrup Shive (February 22, 1913 – June 1, 1984) was an American physicist and inventor. He made notable contributions in electronic engineering and solid-state physics during the early days of transistor development at Bell Laboratories. In particular, he produced experimental evidence that holes could diffuse through bulk germanium, and not just along the surface as previously thought. This paved the way from Bardeen and Brattain's point-contact transistor to Shockley's more-robust junction transistor. Shive is best known for inventing the phototransistor in 1948 (a device that combines the sensitivity to light of a photodiode and the current gain of a transistor), and for the Shive wave machine in 1959 (an educational apparatus used to illustrate wave motion). Early life and education John N. Shive was born in Baltimore, Maryland, on February 22, 1913, and grew up in New Jersey. Shive graduated from Rutgers University with a BS in physics and chemistry in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dark Current (physics)
In physics and in electronic engineering, dark current is the relatively small electric current that flows through photosensitive devices such as a photomultiplier tube, photodiode, or charge-coupled device even when no photons enter the device; it consists of the charges generated in the detector when no outside radiation is entering the detector. It is referred to as reverse bias leakage current in non-optical devices and is present in all diodes. Physically, dark current is due to the random generation of electrons and holes within the depletion region of the device. The charge generation rate is related to specific crystallographic defects within the depletion region. Dark-current spectroscopy can be used to determine the defects present by monitoring the peaks in the dark current histogram's evolution with temperature. Dark current is one of the main sources for noise in image sensors such as charge-coupled devices. The pattern of different dark currents can result in a fix ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John N
John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Second Epistle of John, often shortened to 2 John * Third Epistle of John, often shortened to 3 John People * John the Baptist (died c. AD 30), regarded as a prophet and the forerunner of Jesus Christ * John the Apostle (lived c. AD 30), one of the twelve apostles of Jesus * John the Evangelist, assigned author of the Fourth Gospel, once identified with the Apostle * John of Patmos, also known as John the Divine or John the Revelator, the author of the Book of Revelation, once identified with the Apostle * John the Presbyter, a figure either identified with or distinguished from the Apostle, the Evangelist and John of Patmos Other people with the given name Religious figures * John, father of Andrew the Apostle and Saint Peter * P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bipolar Transistor
A bipolar junction transistor (BJT) is a type of transistor that uses both electrons and electron holes as charge carriers. In contrast, a unipolar transistor, such as a field-effect transistor, uses only one kind of charge carrier. A bipolar transistor allows a small current injected at one of its terminals to control a much larger current flowing between the terminals, making the device capable of amplification or switching. BJTs use two p–n junctions between two semiconductor types, n-type and p-type, which are regions in a single crystal of material. The junctions can be made in several different ways, such as changing the doping of the semiconductor material as it is grown, by depositing metal pellets to form alloy junctions, or by such methods as diffusion of n-type and p-type doping substances into the crystal. The superior predictability and performance of junction transistors quickly displaced the original point-contact transistor. Diffused transistors, along wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avalanche Breakdown
Avalanche breakdown (or avalanche effect) is a phenomenon that can occur in both insulating and semiconducting materials. It is a form of electric current multiplication that can allow very large currents within materials which are otherwise good insulators. It is a type of electron avalanche. The avalanche process occurs when carriers in the transition region are accelerated by the electric field to energies sufficient to create mobile or free electron-hole pairs via collisions with bound electrons. Explanation Materials conduct electricity if they contain mobile charge carriers. There are two types of charge carriers in a semiconductor: free electrons (mobile electrons) and electron holes (mobile holes which are missing electrons from the normally occupied electron states). A normally bound electron (e.g., in a bond) in a reverse-biased diode may break loose due to a thermal fluctuation or excitation, creating a mobile electron-hole pair. If there is a voltage gradient (el ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johnson–Nyquist Noise
Johnson–Nyquist noise (thermal noise, Johnson noise, or Nyquist noise) is the electronic noise generated by the thermal agitation of the charge carriers (usually the electrons) inside an electrical conductor at equilibrium, which happens regardless of any applied voltage. Thermal noise is present in all electrical circuits, and in sensitive electronic equipment (such as radio receivers) can drown out weak signals, and can be the limiting factor on sensitivity of electrical measuring instruments. Thermal noise increases with temperature. Some sensitive electronic equipment such as radio telescope receivers are cooled to cryogenic temperatures to reduce thermal noise in their circuits. The generic, statistical physical derivation of this noise is called the fluctuation-dissipation theorem, where generalized impedance or generalized susceptibility is used to characterize the medium. Thermal noise in an ideal resistor is approximately white, meaning that the power spectral ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capacitance
Capacitance is the capability of a material object or device to store electric charge. It is measured by the change in charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized are two closely related notions of capacitance: ''self capacitance'' and ''mutual capacitance''. An object that can be electrically charged exhibits self capacitance, for which the electric potential is measured between the object and ground. Mutual capacitance is measured between two components, and is particularly important in the operations of the capacitor, a device designed for this purpose as an elementary linear electronic component. Capacitance is a function only of the geometry of the design of the capacitor, e.g., the opposing surface area of the plates and the distance between them, and the permittivity of the dielectric material between the plates. For many dielectric materials, the permittivity and thus the capacitance, is inde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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