10. Translate the following international words without a dictionary.

Centre, class, component, detail, diagram, formula, integral, interval, laboratory, maximum, mechanism, meson, method, model, moment, neutron, parallel, parameter, photon, position, procedure, programme, pulse, radius, spectrum, symmetry, technique.

11. Read and translate word-combinations.

1. Start from the first component

   cooling ionized air outer used	absolute total height barometric metacentric	absolute critical value optimum
   approximate average value zero	emitter collector junction diffused rectifying	algebraic code sign negative positive
   thermal back diffusion deep	differential parametric gain pure	antenna laser gain maser power

2. Start from the second component

junction collector contact region emitter stability

charge carrier electron diffusion solid-state

12. Match the following word-combinations with their translations.

1. effective area 2. ionized region 3. high-frequency gain 4. D.C. gain 5. power gain 6. intrinsic region 7. antenna area 8. short-circuit current gain 9. information gain 10. amplifier gain

a. прирост информации b. усиление по мощности c. усиление на высокой частоте d. усиление усилителя e. усиление по постоянному току f. коэффициент усиления по току в режиме короткого замыкания g. действующая поверхность антенны h. действующая (эффективная) площадь i. ионизированный слой j. область внутренней проводимости

13. Translate word-combinations.

the probability	of measuring of recombining of meeting of correcting of introducing	by (посредством)	eliminating replacing setting up correcting determining
for	obtaining constructing connecting manufacturing reducing	before	adding installing closing designing disappearing

14. Choose as many words from the table of ex. 1 as you can and form sensible sentences.

For example: The difference in potential from one side of the junction to the other is called the height of the potential barrier and is measured in volts.

Specialist reading

15. Read the text “The p-n Junction”. Mark the following sentences as true (t) or false (f).

1. Diffusion is a tendency of charge carriers to move to areas of high density.

2. The free electrons and holes have completely ordered motions in the lattice.

3. On average the N-type region gains holes and loses electrons and the P-type region gains electrons and loses holes.

4. The region to the left of the junction becomes positively charged and the region to the right of the junction becomes negatively charged.

5. If a silicon crystal is doped with donor atoms at one end and with acceptor atoms at the other end, the crystal will have only N-type regions.

6. In Fig.2 the plane AB is the P-N junction.

7. A hole passing into the N-type region, or an electron passing into the P-type region, becomes a majority charge carrier.

The P-N Junction

If a silicon crystal is doped with donor atoms at one end and with acceptor atoms at the other end, the crystal will have both P-type and N-type regions and there will be a junction (Fig. 1) between them. In Fig. 2 the plane AB is the P-N junction; only the free electrons and holes have been shown. Both regions include charge carriers of either sign but in the N-type region electrons are in the majority and in the P-type region holes predominate. In both regions the probability of a minority charge carrier meeting and recombining with a majority charge carrier is high and the minority charge carrier lifetime is short.

Fig. 1. The junction is strong

Fig.2. P-N junction

The free electrons and holes have completely random motions and wander freely in the lattice. However, since there are more electrons to the left of the P-N junction than to the right and more holes to the right of the junction than to the left, on average more electrons cross the junction from left to right than from right to left.

On average, therefore, the N-type region gains holes and loses electrons and the P-type region gains electrons and loses holes. This process is known as diffusion and may be defined as the tendency for charge carriers to move away from areas of high density.

Since the N-type region loses negative charge carriers and gains positive charge carriers and the P-type region loses positive charge carriers and gains negative charge carriers, the region to the left of the junction becomes positively charged and the region to the right of the junction becomes negatively charged. A hole passing into the N-type region, or an electron passing into the P-type region, becomes a minority charge carrier and will probably recombine with a carrier of opposite sign and disappear. However, one region has lost a positive (or negative) charge and the other region has gained a positive (or negative) charge. The movement of holes and electrons across the junction constitutes current and this is known as the diffusion current.