1. Read and memorize the following words.

nonmetal ['non,metl] неметалл

surpass [sa/pa.s] превосходить

solid ['solid] твердое тело, твердое вещество

structure f'strAktfe] структура

purify ['pjusrifai] очищать

transport [traens'po:t] передавать, переносить

dope [doup] легировать, примесь

boron [Ъогэп] бор

phosphorus ['fosf(3)ras] фосфор

arsenic ['a:snik] мышьяк

switch [switf] переключать, переключатель

valence ['veibnsi] валентность

transparent [tr;ens'pear(3)nt] прозрачный

metalloid fmetaloid] металлоид

germanium [djai'meiniam] германий

share [|еэ] делить

neighbouring ['neib(3)riq] соседний intermediate [,int3(:)'mi:dj3t] промежуточный discover [dis'kAva] открывать predict [pri'dikt] предсказывать

hypothetical [,haipo(u)'0etik(3)l] гипотетический, предполагаемый

recognize ['rekagnaiz] признавать

gallium ['gaeliam] галлий

lens [lenz] линза

objective [ob'djektiv] объектив

2. Read arid memorize the following word combinations.

substitutional impurities - примеси замещения

covalent bond - ковапентная связь

wandering electron - блуждающий электрон

n-type silicon - кремний с электронной (n-типа) проводимостью

silvery-grey metalloid - металлоид серебристо-серого цвета

fluorescent lamp - лампа дневного света

index of refraction - коэффициент преломления

wide-angle lens - широкоугольный объектив (линза)

light guide - световод

supply voltage - напряжение питания

2. Read the international words. Guess and memorize their meanings.

atomic, structure, doping, chip, natural, to revolutionize, covalent, extra, crystal, metalloid, position, periodic, hypothetical, economic, to recognize, substance, primary, to attack, fluorescent, to detect, refraction, camera, microscope, objective

Text 5. Semiconductors: Silicon and Germanium Silicon. Silicon is a nonmetallic chemical element. Its density is 2.33 at 25 °C, melting point 2,570 °F (1,410°C). Silicon makes up 27.7 percent of the Earth's crust; it is the second most abundant element in the crust, being surpassed only by oxygen.

Pure silicon is a hard, dark grey solid. Its atomic structure makes it an extremely important semiconductor; highly purified silicon, doped with such elements as boron, phosphorus, and arsenic, it is the basic material used in computer chips, transistors, silicon diodes, and various other electronic circuits and switching devices. Pure silicon does not occur naturally, but can be produced as large crystals from which thousands of silicon chips are made.

The development of the transistor and related semiconductor devices has revolutionized the electronics industry. These devices usually contain substitutional impurities. The two commonest semiconductors are silicon and germanium. Both of these elements have four valence electrons, each shared with a neighboring atom in a covalent bond. In a silicon semiconductor, one of the silicon atoms may be replaced by an atom of arsenic, which has five valence electrons. One electron is left free after the four covalent bonds are formed. At ordinary temperatures, this extra electron is free to move about the crystal. If part of the crystal has many arsenic impurities, this region is called n-type (negative charge) silicon. The wandering electrons act like the free electrons of a metal.

Germanium. Germanium is a silvery-grey metalloid, intermediate in properties between the metals and the nonmetals. Although germanium was not discovered until 1886 by Clemens Winkler, a German chemist, its existence, properties, and position in the periodic system had been predicted in 1871 by the Russian chemist Dmitry Ivanovich Mendeleyev, who called the hypothetical element ekasilicon. Germanium did not become economically significant until after 1945, when its properties as a semiconductor were recognized as being of value in electronics. Many other substances now also are used as semiconductors, but germanium remains of primary importance in the manufacture of transistors and of components for devices such as rectifiers and photocells.

Its specific gravity is 5.3, melting point 1,719.3 °F (937.4 °C). The occurrence of germanium in the Earth's crust is low - about 1.5 parts per million. The element is brittle rather than ductile; the atoms in its crystals are arranged as are the carbon atoms in diamond. It is not attacked by air at room temperature but is oxidized at 1,100- 1,300°F (600 - 700°C).

For use in electronic devices, germanium is purified. The highly pure germanium is then melted and "doped" to produce desired electronic characteristics by adding minute amounts of arsenic, gallium, or other elements. Finally, crystals are generated from the melt at carefully controlled temperatures.

In addition to its applications in electronic devices, germanium is used as a component of alloys and in phosphors for fluorescent lamps. Because germanium is transparent to infrared radiation, it is useful in equipment used for detecting and measuring such radiation. The high index of refraction of germanium dioxide makes it valuable as a component of glasses used in optical devices, such as wide-angle lenses for cameras and microscope objectives.

Notes

make up — составлять

it is the second most abundant element in the crust - он занимает второе место по наличию в земной коре

as being of value in electronics - применяемый в электронике of primary importance - первостепенное значение

2. Form adjectives from the verbs by adding suffixes. Translate and memorize the words.

Suffixes -ENT, -ANT, -IVE

Model: to depend - dependent, to effect - effective

to differ, to conduct, to act, to resist, to decorate, to protect, to adapt, to excel, to signify, to interact, to attract, to create, to radiate, to product

2. Translate the following word combinations.

control system, system control, infrared radiation measurement, semiconductor memory chip, high-speed integrated circuit, negative resistance device, highly purified doped silicon, carefully controlled temperature, silvery-gray surface, chromium oxide coating

2. Answer the following questions.

1. Is silicon a metal or a dielectric? 2. What are the properties of silicon? 3. What is silicon used for? 4. What are the two commonest semiconductors? 5. Why are silicon and germianium doped? 6. Who predicted the existence of germanium? 7. Why is germanium purified? 8. What elements are added to germanium? 9. What propery of germanium makes it possible to use it for detecting and measuring infrared radiation? 10. How do we use germanium dioxide in optical devices?

2. Translate the following into English using prepositions where necessary.

1. В восемь часов утра. 2. В воскресенье. 3. Через две недели. 4. В прошлом году. 5. Без десяти шесть. 6. На будущей неделе. 7. Вереду. 8. Позавчера. 9. Через полтора года. 10. В двадцать минут пятого. 11. В течение месяца. 12. Послезавтра. 13. Через десять секунд. 14. В 1998 году. 15. К восьми часам утра. 16. В полдень. 17. Прошлой ночью. 18. Через пять миллисекунд. 19. В полночь. 20. Завтра к вечеру.

2. Fill in prepositions.

1. Silicon is doped ... such elements as boron, phosphorus, and arsenic. 2. Germanium is intermediate ... properties between the metals and the nonmetals. 3. The atoms ... germanium crystals are arranged as are the carbon atoms ... diamond. 4. The crystals are generated ... the melt ... carefully controlled temperatures. 5. Germanium dioxide is used ... optical devices such as wide-angle lenses ... cameras. 6. It would be difficult to imagine a world ... plastics. 7. Electronics is concerned ... the design of circuits to generate and modify electric currents. 8. Electronics engineering deals ... such low current applications as radio communication, computers, radar, etc. 9. Positive pulses ... this TV set circuit are synchronized ... respect to each other. 10. The maximum voltage that doesn't cause any puncture ... the material is the dielectric strength of that material. 11. We could not do ... diodes in most digital circuits. 12. Copper is combined ... other metals to form alloys. 13.... 1930 the term electronics was introduced ... radio.

2. Translate the following sentences paying attention to compound prepositions according to, by means of, due to, in spite of, owing to, since, toward, until, within.

1. Conduction is due to a flow of free electrons from points at low potential to points at higher potential. 2. The familiar light bulb gives off light owing to its incandescence. 3. Metal and dielectric films are deposited by means of sputtering. 4. A graphics software package enables a computer to process graphic images by means of mathematical language. 5.. A computer displays images on a graphics display screen by means of an electron beam that sweeps the screen many times each second. 6. Since the wiring between cells can occupy three-quarters of the chip area it is important to optimize this design stage. 7. Coherent light guides are used to transport optical images, since an image projected onto one end of the guide reappears at the other end.

8. Computer graphics have found widespread use in printing, product design and manufacturing, scientific research, and entertainment since the 1960s.

9. It is very important to connect electrolytic capacitors according to the polarity marked on their case. 10. Diodes can be classified according to their construction and function. 11. The automated systems use adaptive control to drive the process toward the optimal state. 12. A capacitor stores up charge until the voltage on its plates equals the supply voltage. 13. A final test is performed on the chip to determine whether it operates within the specified standards. 14. Resistors can have a fixed value of resistance, or they can be made variable or adjustable within a certain range.

10. Translate the following jokes paying attention to prepositions. Explain the idea of the jokes.

A German student, who did not know English very well, came to a post-office in London. In one hand he had a letter in an envelope and in the other hand he held a stamp. He went up to the girl who worked there and gave her the stamp and the envelope.

"No, no," she said. "You must stick the stamp on yourself."

"Why must I stick the stamp on myself?" asked the student. "I want to send a letter but not myself!"

A scientist has a new theory on the evolution of the mushroom. He says that since the mushroom grows in damp places, it is only natural that it be in the shape of an umbrella.

• * ф

THE SECRETARY KNOWS THE JOB WELL (As outlined by the secretary over the phone) A.M.

"He hasn't come in yet."

"I expect him in any minute."

"He just sent a word in he would be a little late."

"He has been in, but he went out again."

"He's gone to lunch."

P.M.

"I expect him in any minute."

"He hasn't come back yet. Can I take a message?"

"He's somewhere in the building. His hat is here."

"Yes, he was in, but he went out again."

"I don't know whether he will be back or not."

"No, he's gone for the day."

• * *

A foreigner in London stopped a man and asked: "Excuse me, what is time?"

The Englishman politely replied: "You know, by a strange coincidence, I'm philosophically minded too, but I haven't yet been able to find out the answer to this great problem."

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