Вивчення термінології за темою модуля. Exercise 1. Answer the following questions

Exercise 1. Answer the following questions.

1) What gives the transistor an advantage over the vacuum tube?

2) What does simple transistor consist of?

3) How is it possible to regulate semiconductors’ conductivity?

4) Why don’t we use for doping semiconductors such metals as copper or aluminium with loosely bounded electrons to stimulate n-type conductivity?

5) Do you know something about rectifiers on semiconductors? How do they work?

6) Which common household appliances and instruments use transistors and integrated circuits?

7) Why is low consumption of energy is so important for modern electronic equipment and devices?

Exercise 2. Insert the words the best suited to the sentences using the list below. Each of words in the list is used only once. Then listen and check your guesses.

Semiconductor materials may be divided into two _________ groups: intrinsic and extrinsic. An intrinsic semiconductor is chemically very pure, and its __________ is poor. Some common intrinsic semiconductors are single ________ of silicon, germanium, and gallium arsenide. These may be converted into the more useful extrinsic _____________ by the addition of small amounts of impurities. This process, known as doping, alters the ___________ properties of the semiconductor and _______ its conductivity.

For example, the atom of an intrinsic semiconductor such as _________ silicon has four electrons in its outermost shell. These electrons attach the ________ atom to its neighboring atoms and so are not free to move through the solid. Accordingly, since electric ________ relies on charge motion, pure silicon is a poor _________ of electricity. If arsenic atoms, with five outer electrons, are _________ for some of the silicon atoms, the fifth electron is not needed for binding to adjacent atoms and is free to move through the solid. Thus, ________ silicon with arsenic improves the silicon’s conductivity. On the other hand, if a silicon atom is _______ by an indium atom, which has three valence________, an electron is missing from one covalent bond, _______ an empty space, so-called hole. This hole can move about, just as the free electron could. A region with such indium ___________ is called p-type silicon because the holes act like carriers of positive charges, and thus they also serve to _________ the silicon’s conductivity. An extrinsic semiconductor is commonly _________ as n - or p -type, depending on whether the impurity added has an excess of negative charge (n -type) or a deficiency of negative _________ (p -type).

In the p-n-p type transistor, the first part, ___________ the emitter, is doped to give it an excess of positive charges; the second, the base, is doped to give it _______ negative charges; and the third, the collector, is doped like the first part to give it an excess of _________ charges.

Date: 2016-06-09; view: 453; Нарушение авторских прав