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Diodes. Контрольный перевод
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Министерство высшего и среднего специального образования

Московский государственный университет леса

Кафедра иностранных языков


Контрольный перевод

На тему:

«Diodes»
Выполнил

Студент группы ИТ-21

Захаров Алексей

Проверил:

Доцент Абрамова Алла Викторовна

Москва 2011

In electronics, a diode is a two-terminal electronic component that conducts electric current in only one direction. The term usually refers to a semiconductor diode, the most common type today. This is a crystalline piece of semiconductor material connected to two electrical terminals. A vacuum tube diode (now little used except in some high-power technologies) is a vacuum tube with two electrodes: a plate and a cathode.

The most common function of a diode is to allow an electric current to pass in one direction (called the diode's forward direction) while blocking current in the opposite direction (the reverse direction). Thus, the diode can be thought of as an electronic version of a check valve. This unidirectional behavior is called rectification, and is used to convert alternating current to direct current, and to extract modulation from radio signals in radio receivers.

However, diodes can have more complicated behavior than this simple on-off action. This is due to their complex non-linear electrical characteristics, which can be tailored by varying the construction of their P-N junction. These are exploited in special purpose diodes that perform many different functions. For example, specialized diodes are used to regulate voltage (Zener diodes), to electronically tune radio and TV receivers (varactor diodes), to generate radio frequency oscillations (tunnel diodes), and to produce light (light emitting diodes). Tunnel diodes exhibit negative resistance, which makes them useful in some types of circuits.

Diodes were the first semiconductor electronic devices. The discovery of crystals' rectifying abilities was made by German physicist Ferdinand Braun in 1874. The first semiconductor diodes, called cat's whisker diodes, developed around 1906, were made of mineral crystals such as galena. Today most diodes are made of silicon, but other semiconductors such as germanium are sometimes used.

History

Although the crystal semiconductor diode was popular before the thermionic diode, thermionic and solid state diodes were developed in parallel.

In 1873 Frederick Guthrie discovered the basic principle of operation of thermionic diodes. Guthrie discovered that a positively charged electroscope could be discharged by bringing a grounded piece of white-hot metal close to it (but not actually touching it). The same did not apply to a negatively charged electroscope, indicating that the current flow was only possible in one direction.

Thomas Edison independently rediscovered the principle on February 13, 1880. At the time, Edison was investigating why the filaments of his carbon-filament light bulbs nearly always burned out at the positive-connected end. He had a special bulb made with a metal plate sealed into the glass envelope. Using this device, he confirmed that an invisible current flowed from the glowing filament through the vacuum to the metal plate, but only when the plate was connected to the positive supply.

Edison devised a circuit where his modified light bulb effectively replaced the resistor in a DC voltmeter. Edison was awarded a patent for this invention in 1884. There was no apparent practical use for such a device at the time. So, the patent application was most likely simply a precaution in case someone else did find a use for the so-called Edison effect.

About 20 years later, John Ambrose Fleming (scientific adviser to the Marconi Company and former Edison employee) realized that the Edison effect could be used as a precision radio detector. Fleming patented the first true thermionic diode in Britain on November 16, 1904 (followed by U.S. Patent 803,684 in November 1905).

In 1874 German scientist Karl Ferdinand Braun discovered the "unilateral conduction" of crystals. Braun patented the crystal rectifier in 1899. Copper oxide and selenium rectifiers were developed for power applications in the 1930s.

At the time of their invention, such devices were known as rectifiers. In 1919, William Henry Eccles coined the term diode from the Greek roots dia, meaning “through”, and ode (from ὅδος), meaning “path”.

Thermionic and gaseous state diodes

Thermionic diodes are thermionic-valve devices (also known as vacuum tubes, tubes, or valves), which are arrangements of electrodes surrounded by a vacuum within a glass envelope. Early examples were fairly similar in appearance to incandescent light bulbs.

In thermionic valve diodes, a current through the heater filament indirectly heats the cathode, another internal electrode treated with a mixture of barium and strontium oxides, which are oxides of alkaline earth metals; these substances are chosen because they have a small work function. (Some valves use direct heating, in which a tungsten filament acts as both heater and cathode.) The heat causes thermionic emission of electrons into the vacuum. In forward operation, a surrounding metal electrode called the anode is positively charged so that it electrostatically attracts the emitted electrons. However, electrons are not easily released from the unheated anode surface when the voltage polarity is reversed. Hence, any reverse flow is negligible.

For much of the 20th century, thermionic valve diodes were used in analog signal applications, and as rectifiers in many power supplies. Today, valve diodes are only used in niche applications such as rectifiers in electric guitar and high-end audio amplifiers as well as specialized high-voltage equipment.

Semiconductor diodes

A modern semiconductor diode is made of a crystal of semiconductor like silicon that has impurities added to it to create a region on one side that contains negative charge carriers (electrons), called n-type semiconductor, and a region on the other side that contains positive charge carriers (holes), called p-type semiconductor. The diode's terminals are attached to each of these regions. The boundary within the crystal between these two regions, called a PN junction, is where the action of the diode takes place. The crystal conducts conventional current in a direction from the p-type side (called the anode) to the n-type side (called the cathode), but not in the opposite direction.

Another type of semiconductor diode, the Schottky diode, is formed from the contact between a metal and a semiconductor rather than by a p-n junction.

Current–voltage characteristic

A semiconductor diode’s behavior in a circuit is given by its current–voltage characteristic,. The shape of the curve is determined by the transport of charge carriers through the so-called depletion layer or depletion region that exists at the p-n junction between differing semiconductors. When a p-n junction is first created, conduction band electrons from the N-doped region diffuse into the P-doped region where there is a large population of holes (vacant places for electrons) with which the electrons “recombine”. When a mobile electron recombines with a hole, both hole and electron vanish, leaving behind an immobile positively charged donor on the N-side and negatively charged acceptor on the P-side. The region around the p-n junction becomes depleted of charge carriers and thus behaves as an insulator.

However, the width of the depletion region (called the depletion width) cannot grow without limit. For each electron-hole pair that recombines, a positively charged dopant ion is left behind in the N-doped region, and a negatively charged dopant ion is left behind in the P-doped region. As recombination proceeds more ions are created, an increasing electric field develops through the depletion zone which acts to slow and then finally stop recombination. At this point, there is a “built-in” potential across the depletion zone.

If an external voltage is placed across the diode with the same polarity as the built-in potential, the depletion zone continues to act as an insulator, preventing any significant electric current flow (unless electron/hole pairs are actively being created in the junction by, for instance, light). This is the reverse bias phenomenon. However, if the polarity of the external voltage opposes the built-in potential, recombination can once again proceed, resulting in substantial electric current through the p-n junction (i.e. substantial numbers of electrons and holes recombine at the junction). For silicon diodes, the built-in potential is approximately 0.7 V (0.3 V for Germanium and 0.2 V for Schottky). Thus, if an external current is passed through the diode, about 0.7 V will be developed across the diode such that the P-doped region is positive with respect to the N-doped region and the diode is said to be “turned on” as it has a forward bias.

At very large reverse bias , beyond the peak inverse voltage or PIV, a process called reverse breakdown occurs which causes a large increase in current (i.e. a large number of electrons and holes are created at, and move away from the P-N junction) that usually damages the device permanently. The avalanche diode is deliberately designed for use in the avalanche region. In the zener diode, the concept of PIV is not applicable. A zener diode contains a heavily doped p-n junction allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material, such that the reverse voltage is “clamped” to a known value (called the zener voltage), and avalanche does not occur. Both devices, however, do have a limit to the maximum current and power in the clamped reverse voltage region. Also, following the end of forward conduction in any diode, there is reverse current for a short time. The device does not attain its full blocking capability until the reverse current ceases.


В электронике, диод это двух контактный электронный компонент, который проводит электрический ток только в одном направлении. Термин обычно относится к полупроводниковому диоду, наиболее распространенному типу диодов сегодня. Это кристаллическая часть полупроводникового материала, соединенного с двумя электрическими контактами. Вакуумная диодная трубка (в настоящее время практически не используется, за исключением некоторых мощных технологий), это вакуумная трубка с двумя электродами: пластиной и катодом.

[…]

Хотя, кристальный полупроводниковый диод был популярен до термоионного диода; термоионное и твердое состояния диодов были разработаны параллельно. В 1873 году Фредерик Гутри открыл основной принцип работы термоионных диодов. Гутри обнаружил, что положительно заряженный электроскоп может быть разряжен путем привлечения заземленной части раскаленного металла близко к нему (но не прикасаясь к нему). Это же не распространяется на отрицательно заряженный электроскоп, что означает, что электрический ток может протекать только в одном направлении.

[…]

В термоионных клапанных диодах, ток, текущий через нагреватель накаливания, косвенно нагревает катод, другой внутренний электрод обрабатывают смесью оксидов бария и стронция, являющихся оксидами щелочноземельных металлов. Эти вещества выбраны потому, что они имеют малую рабочую функцию (в некоторых клапанах используют прямой нагрев, в котором нить накала из вольфрама действует как подогреватель и катод.) Тепло вызывает термоионную эмиссию электронов в вакууме. В прямом действии, окруженный металлический электрод, называемый анодом, положительно заряжен так, что он электростатически притягивает вылетевшие электроны. Однако, электроны не легко освобождается от неотапливаемых поверхностей анода, когда напряжение полярности противоположно. Следовательно, любой обратный поток незначителен.

[…]

Поведение полупроводникового диода в цепи определяется его вольт-амперная характеристика. Форма кривой определяется перемещением носителей заряда через так называемый слой истощения или обедненной области, который существует на P-N переходе между различными полупроводниками. Когда P-N переход производится впервые, зоны проводимости электронов из n-легированной области диффундируют в р-легированной области, где большая численность дырок (свободные места для электронов), с которой электроны "рекомбинируют". Когда подвижный электрон рекомбинирует с дыркой, и дырка и электрон исчезают, оставляя за собой неподвижные положительно заряженные доноры на N-стороне и отрицательно заряженных акцепторов на Р-стороне. Область вокруг P-N перехода истощается носителями заряда и, следовательно, ведет себя как диэлектрик.



Ability (n)

[ə'bɪlətɪ]

Способность

Alkaline (n)

['ælk(ə)laɪn]

Щелочь

Approximately (adv)

[ə'prɔksɪmətlɪ]

Около

Attain (v)

[ə'teɪn]

Достичь

Avalanche (n)

['æv(ə)lɑːn(t)ʃ]

Лавина

Band (n)

[bænd]

Зона

Behavior (n)

[bɪ'heɪvjər]

Поведение

Bias(n)

['baɪəs]

Смещение

Boundary (n)

['baund(ə)rɪ]

Граница

Breakdown(n)

['breɪkdaun]

Пробой

Bulb (n)

[bʌlb]

Лампа

Capability (n)

[ˌkeɪpə'bɪlətɪ]

Возможность

Carrier (n)

['kærɪə]

Носитель

Charge (n)

[ʧɑːʤ]

Заряд

Circuit (n)

['sɜːkɪt]

Цепь

Current (n)

['kʌr(ə)nt]

Ток

Current-voltage (a)

['kʌr(ə)nt 'vəultɪʤ]

Вольт-амперная

Curve (n)

[kɜːv]

Кривая

Device (n)

[dɪ'vaɪs]

Устройство

Diffuse (n)

[dɪ'fjuːs]

Диффузия

Direction (n)

[dɪ'rekʃ(ə)n]

Направление

Emit (v)

[ɪ'mɪt]

Вылететь

Employee (n)

[ˌɪmplɔɪ'iː]

Сотрудник

Envelope (n)

['envələup]

Оболочка

Equipment (n)

[ɪ'kwɪpmənt]

оборудование

Filament (n)

['fɪləmənt]

Нить

Hence (adv)

[hen(t)s]

Следовательно

Impurity (n)

[ɪm'pjuərətɪ]

Примесь

Insulator (n)

['ɪnsjəleɪtə]

Диэлектрик

Invention (n)

[ɪn'venʃ(ə)n]

Изобретение

Junction (n)

['ʤʌŋkʃ(ə)n]

Переход

Layer (n)

['leɪə]

Слой

Mobile (a)

[məu'biːl]

Подвижный

Negligible (adv)

['neglɪʤəbl]

Незначительно

Niche (n)

[nɪʃ]

Ниша

Opposite (a)

['ɔpəzɪt]

Противоположный

Precision (n)

[prɪ'sɪʒ(ə)n]

Точность

Rectification (n)

[ˌrektɪfɪ'keɪʃ(ə)n]

Выпрямление

Reverse (a)

[rɪ'vɜːs]

Обратный

Semiconductor (n)

[ˌsemɪkən'dʌktə]

Полупроводник

Shape (n)

[ʃeɪp]

Форма

Significant (a)

[sɪg'nɪfɪkənt]

Значительный

Supply (n)

[sə'plaɪ]

Источник питания

Terminal (n)

['tɜːmɪn(ə)l]

Контакт

To tailor (v)

['teɪlə]

Адаптировать

To vanish (v)

['vænɪʃ]

Исчезать

Unilateral (a)

[ˌjuːnɪ'læt(ə)r(ə)l]

Односторонний

Valence (a)

['veɪl(ə)n(t)s]

Валентный

Valve (n)

[vælv]

Клапан

White-hot metal (n)

[(h)waɪt- hɔt 'met(ə)l]

Раскаленный металл



  1. Tunnel diodes exhibit negative resistance, which makes them useful in some types of circuits.

Makes – Present Simple, A.V. от глагола to make

  1. ^ The most common function of a diode is to allow an electric current to pass in one direction (called the diode's forward direction) while blocking current in the opposite direction (the reverse direction).

the most common – прилагательное, превосходная степень, от common

called – Participle II, в функции определения, от глагола to call

blocking – герундий, в функции обстоятельства

  1. In 1873 Frederick Guthrie discovered the basic principle of operation of thermionic diodes.

Discovered – Past Simple, A.V. от глагола to discover

  1. Thus, the diode can be thought of as an electronic version of a check valve.

Can be thought – модальный глагол can в Present Simple + be thought – Passive Infinitive

  1. This unidirectional behavior is called rectification, and is used to convert alternating current to direct current, and to extract modulation from radio signals in radio receivers.

Is called – Present Simple, P. V. от глагола to call

Alternating – Participle I, в функции определения

  1. The first semiconductor diodes, called cat's whisker diodes, developed around 1906, were made of mineral crystals such as galena.

Cat`s whisker – притяжательный падеж

Were made – Past Simple, P.V. от глагола to make


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