Semiconductors — New Branch  of Science

The successes of physics of semiconductors attained in our country are linked with the name of the famous Soviet scientist — Academician A. F. Yoffe. He began to concentrate on physics of semiconductors in the early thirties. He had a wide range of scientific interests. His research involved light waves, the mechanism of plastic deformation, the photoelectric effect.

At that time little importance had been attached to the ability of semiconductors to absorb heat and produce electricity since the efficiency was extremely low. And then Academician Yoffe declared that the research into semiconductors had points of theoretical interest and held out great promise for commercial development. This sounded quite fantastic at that time.

It did not take the scientist too much time to prove his point- Semiconducting elements with an improved efficiency were developed shortly before World War II. Yoffe drew into the research of semiconducting materials a number of young research workers, his wife being his closest assistant and associate.

The data compiled by Yoffe as a result of his fundamental research enabled him to formulate a systematic theory of semiconductors which paved the way for   their large scale commercial utilization.

The formerly insignificant efficiency of the semiconductors began to climb and promised to rise up to 25 per cent. Semiconductors have found their way to radio-receivers and television sets, they became essential in measuring techniques thanks to their being extraordinarily sensitive to light, temperature and atmospheric humidity. However, all this was only the beginning in this new branch of physics. Yoffe was after problems that were more complex and of greater value.

The last thing one could call Yoffe was an armchair scientist. He was against experiment for the sake of experiment. He believed that research had to be organized so that physics would provide the scientific foundation for the technology of socialism.

In studying the theory' of semiconductors Yoffe had in mind the direct conversion of solar energy into electricity. He thought it abnormal that of the energy so generously sent' by the sun only a small fraction was used by man, only a quarter of one per cent. And even making use of this fraction involved tremendous difficulties: the mining of coal, the construction of turbines and other equipment. Scientists working in this field were looking for a way of converting solar energy and making it serve people directly. Yoffe perceived such a possibility in semiconducting thermal elements in which an electric current is induced by ordinary light.
A solar battery 100 km. long could provide enough power to meet the world's demands.

A long series of experiments and preliminary theoretical studies enabled the scientists to find thermo-electric systems with an extraordinary high efficiency, and develop a kind of a miniature power plant. Electric stations of this type are now being made use of. Solar batteries are successfully operating on board the Soviet spaceships. They are well known in the northern areas of our country and in the Antarctic, in India and Indonesia. In the absence of the usual electric transmission lines they serve as power sources for local telephone exchanges and transmitters.

Much of what was discovered and proved by Yoffe has now become part of ABC of physics. The great future of semiconductors is a generally recognized fact. Many industries in the Soviet Union are based on semiconducting elements. Photoelectric elements controlling the operation of rolling mills are used as quality checks. A new branch of industry — helio engineering — has come into being.
Semiconductors are widely used in practical farming.

Yoffe noticed that semiconducting elements may serve equally well as sources of heat and cold. Semiconductor refrigerators have been developed. In our age, semiconductors mark a new stage in the history of physics, a stage linked with the name of Academician Yoffe who was posthumously awarded the Lenin Prize for theoretical and experimental research into the properties of semiconductors and for evolving the theory of thermo-electric generators.

DIALOGUE

A group of students are having practical training in the laboratory of semiconductors. The demonstrator asks the students about the properties and uses of semiconducting materials.

Demonstrator: Comrade Ivanov! Can you tell me what a semiconductor is?

Ivaоnоv:          Certainly, I can. A semiconductor is a substance that conducts electricity with the 

                        help of electrons, but less effectively than metals do, yet much better than

                        insulators.  Hence the name — "Semiconductors".

Demonstrator: Name, some semiconductors, please.

Student:           These are all the minerals, many chemical elements  and  metals.

Demonstrator: And what about chemical and organic compounds?

Student:           Many chemical and organic compounds are semiconductors too.

Demonstrator: What properties do minerals and crystals possess?

Student:            As far as I know their conductivity increases with heating and falls with cooling.

Demonstrator:  Is it the only property you know of?

Student:            Sorry, I've forgotten to mention their sensitivity to light too. For the chemical

                         properties of germanium may change under the action of light.

Demonstrator:  And radiation as well, is it not so?

Student:            Of course, it is,

Demonstrator:  Can you tell me anything about the application of semiconductors?

Student:            Semiconductors play an important part in very many fields of industry and

                         engineering. They are so widely used now that it is difficult to mention all their 

                         applications.

Demonstrator:  Still name some of them, please!

Student:            Semiconductors are used for transforming light and heat energy into electrical 

                         energy, They can generate heat or cold from electricity. Besides, semiconductors 

                         are used for reproduction of sounds, for transmission of signals, automatic control,

                         for switching on engines.

Demonstrator: That'll do.

EXERCISES

I.        Read the following words:

a)  with the stress on the first syllable: interest, area, promise, formulate, organise, generous, solar, ordinary, operate, local, element;

b) with the stress on the second syllable: success, efficiency, declare, develop, research, assosiate, enable, tremendous, preliminary, award, absorb, improve;

c)  with the stress on the last syllable but one: scientific, electric, fantastic,  fundamental.

II.         Pick upsynonymical pairs out of the following list of words:

to attain, investigation, since, to convert, to utilize, huge, sufficient, to demand, common, to regulate, ordinary, to achieve, research, significance, as, branch, to observe, to transform, to make use of, tremendous, enough, to require, usual, to control,

III.         Pick up antonymical pairs out of the following list of words;
early, narrow, low, to rise up, complex, to send, to find, absence, late, wide, high, to lower, to receive, to look for, simple, presence.

IV.        Read the dialogue. Learn the parts of the demonstrator and the student.

V.        Put questions to the text.

VI.        Choose one of the topics below and prepare to talk about it:

I. Academician A. F. Yoffe and his scientific activity. 2. The. theory of semiconductors at that time. 3. Academician Yoffe's' views upon scientific research . 4. The problem of direct conversion of solar energy into electricity. 5. The use of semiconductors nowadays.