The Schottky effect or field enhanced thermionic emission is a phenomenon in condensed matter physics named after Walter H. Schottky. In electron emission devices, especially electron guns, the thermionic electron emitter will be biased negative relative to its surroundings. This creates an electric field of magnitude F at the emitter surface. Without the field, the surface barrier seen by an escaping Fermi-level electron has height W equal to the local work-function. The electric field lowers the surface barrier by an amount ΔW, and increases the emission current. It can be modeled by a simple modification of the Richardson equation, by replacing W by (W − ΔW). This gives the equation[1][2]
where J is the emission current density, T is the temperature of the metal, W is the work function of the metal, k is the Boltzmann constant, qe is the Elementary charge, ε0 is the vacuum permittivity, and AG is the product of a universal constant A0 multiplied by a material-specific correction factor λR which is typically of order 0.5.
Schottky-emitter electron source of an Electron microscope
Electron emission that takes place in the field-and-temperature-regime where this modified equation applies is often called Schottky emission. This equation is relatively accurate for electric field strengths lower than about 108 V m−1. For electric field strengths higher than 108 V m−1, so-called Fowler–Nordheim (FN) tunneling begins to contribute significant emission current. In this regime, the combined effects of field-enhanced thermionic and field emission can be modeled by the Murphy–Good equation for thermo-field (T-F) emission.[3] At even higher fields, FN tunneling becomes the dominant electron emission mechanism, and the emitter operates in the so-called "cold field electron emission (CFE)" regime.
Thermionic emission can also be enhanced by interaction with other forms of excitation such as light.[4] For example, excited Cs-vapours in thermionic converters form clusters of Cs-Rydberg matter which yield a decrease of collector emitting work function from 1.5 eV to 1.0–0.7 eV. Due to long-lived nature of Rydberg matter this low work function remains low which essentially increases the low-temperature converter’s efficiency.[5]
^
Kiziroglou, M. E.; Li, X.; Zhukov, A. A.; De Groot, P. A. J.; De Groot, C. H. (2008). "Thermionic field emission at electrodeposited Ni-Si Schottky barriers" (PDF). Solid-State Electronics. 52 (7): 1032–1038. Bibcode:2008SSEle..52.1032K. doi:10.1016/j.sse.2008.03.002.
^
Orloff, J. (2008). "Schottky emission". Handbook of Charged Particle Optics (2nd ed.). CRC Press. pp. 5–6. ISBN 978-1-4200-4554-3.
^
Murphy, E. L.; Good, G. H. (1956). "Thermionic Emission, Field Emission, and the Transition Region". Physical Review. 102 (6): 1464–1473. Bibcode:1956PhRv..102.1464M. doi:10.1103/PhysRev.102.1464.
^
Mal'Shukov, A. G.; Chao, K. A. (2001). "Opto-Thermionic Refrigeration in Semiconductor Heterostructures". Physical Review Letters. 86 (24): 5570–5573. Bibcode:2001PhRvL..86.5570M. doi:10.1103/PhysRevLett.86.5570. PMID 11415303.
^
Svensson, R.; Holmlid, L. (1992). "Very low work function surfaces from condensed excited states: Rydber matter of cesium". Surface Science. 269/270: 695–699. Bibcode:1992SurSc.269..695S. doi:10.1016/0039-6028(92)91335-9.
The Schottkyeffect or field enhanced thermionic emission is a phenomenon in condensed matter physics named after Walter H. Schottky. In electron emission...
The Schottky diode (named after the German physicist Walter H. Schottky), also known as Schottky barrier diode or hot-carrier diode, is a semiconductor...
A Schottky barrier, named after Walter H. Schottky, is a potential energy barrier for electrons formed at a metal–semiconductor junction. Schottky barriers...
increases the emission current. This is known as the Schottkyeffect (named for Walter H. Schottky) or field enhanced thermionic emission. It can be modeled...
physicist Walter H. Schottky formulated a theory predicting the Schottkyeffect, which led to the Schottky diode and later Schottky transistors. For the...
A Schottky defect is an excitation of the site occupations in a crystal lattice leading to point defects named after Walter H. Schottky. In ionic crystals...
electrons from an electrode by virtue of its temperature Schottky emission, due to the: Schottkyeffect or field enhanced thermionic emission Field electron...
"The Schottkyeffect in low frequency circuits". Physical Review. 26 (1): 71–85. Bibcode:1925PhRv...26...71J. doi:10.1103/PhysRev.26.71. Schottky, W. (1918)...
(metal–semiconductor field-effect transistor) is a field-effect transistor semiconductor device similar to a JFET with a Schottky (metal–semiconductor) junction...
1017/S1464793101005607. PMID 11396846. S2CID 14973015. Johnson, J. B. (1925). "The Schottkyeffect in low frequency circuits". Physical Review. 26 (1): 71–85. Bibcode:1925PhRv...
the metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor (FET), most commonly fabricated...
The Schottky anomaly is an effect observed in solid-state physics where the specific heat capacity of a solid at low temperature has a peak. It is called...
Michigan). His doctoral thesis at Cornell was titled "The Anomalous SchottkyEffect for Oxygenated Tungsten." In 1925, while completing his master's degree...
circuit protection, temperature protection Quadrant III operations – Schottkyeffect Power supplies – power supply unit (PSU), short-circuit protection...
effect can be safely ignored. For most applications, the effect is also negligible for Schottky diodes. The reverse current ceases abruptly when the stored...
commonly known as a Schottky diode. This is included in the table because some silicon power IGFETs have a parasitic reverse Schottky diode formed between...
Kennicutt–Schmidt law, above Schottkyeffect – Walter H. Schottky Schröter effect – Johann Hieronymus Schröter Schülen–Wilson effect – see Wilson effect, below Schuler...
wellenmechanische Tunneleffekt was used in 1931 by Walter Schottky. The English term tunnel effect entered the language in 1932 when it was used by Yakov...
multi-gate MOSFET or multi-gate field-effect transistor (MuGFET) refers to a metal–oxide–semiconductor field-effect transistor (MOSFET) that has more than...
at the sliding PN junction or Schottky junction is analogous to the generation of photo-current in the photovoltaic effect, and the only difference is that...
The junction field-effect transistor (JFET) is one of the simplest types of field-effect transistor. JFETs are three-terminal semiconductor devices that...
field. Frenkel later developed a microscopic model, similar to the Schottkyeffect, to explain Poole's results more accurately. In this paper published...
account along with concepts such as quantum tunnelling and behavior such as Schottky barrier effects, as well as including models such as asperities for contacts...
Global Information
