Головна

SPECIALIST READING

  1. After reading
  2. Before reading
  3. Before reading the text get to know with the following word-combinations;
  4. Break the paragraph into short sections, practise reading it. Prepare model reading of the passage.
  5. Comment on the phonetic phenomena to be observed in the following exercises. Practise reading them.
  6. F. Practise reading the sentences below. Concentrate on the influence of rhythm on the stress pattern of compound adjectives.
  7. II. READING OF CONSONANTS

21. Read the text "The Forward-Biased P-N Junction" only once. How much can you remember? Answer these questions without additional reading.

1. When are holes caused to drift towards the junction?

2. What end of the crystal are electrons repelled from?

3. What reduces both the width of the depletion layer and the height of the potential barrier?

4. What allows majority charge carriers of lower energy to cross the junction?

5. Why is there a net majority charge carrier current across the junction?

6. How does the current change entering the P-type region and leaving the N-type region?

If you failed try to answer these questions again after doing the exercises given below the text.

If a battery is connected across the crystal in the direction shown in the figure below, holes are repelled from the positive end of the crystal and are caused to drift towards the junction; and electrons are repelled from the negative end of the

The drift of holes and electrons towards the junction reduces both the width of the depletion layer and the height of the potential barrier.

crystal and also drift towards the junction. This drift of holes and electrons towards the junction reduces both the width of the depletion layer and the height of the potential barrier, And the junction is said to be forward biased. The reduction in the height of the potential barrier allows majority charge carriers of lower energy to cross the junction and since the minority charge carrier current remains constant, There is a net majority charge carrier current across the junction from the P-type region to the N-type region. This current increases very rapidly with increase in the forward bias voltage.

The holes drifting through the P-tуре region towards the P-N junction may be considered to have been injected by the positive terminal of the battery. Some of these holes may recombine with electrons diffusing across the junction in the other direction and so the hole current across the junction is slightly (трохи) less than the injected hole current. After they have passed across the junction the holes recombine with the excess electrons in the N-type region and the electrons that have not recombined cross the junction. The total current is the sum of the electron and hole currents and is constant throughout the crystal. The current enters the P-type region as a hole current and leaves the N-type region as an electron current.

22. Study the text and translate the following:

- Батарея приєднана до кристалу

- Змушені зміщуватися до переходу

- Зменшує як ширину збідненого шару, так і висоту потенційного бар'єру

- Вважається, що перехід зміщений вперед

- Тому що ток неосновних носіїв заряду постійний

- Повний струм основних носіїв заряду

- Струм посилюється дуже швидко

- Зі збільшенням напруги прямого зміщення

- Вважається, що дірки були додані

- Електрони, що поширюються (диффундирующие) через перехід

- Надлишкові електрони

- По всьому кристалу

- Дірковий струм і електричний струм

Translate | Fill in the gaps.


Language Work | Put the verbs in brackets into the correct form. | Use your own ideas to complete the sentences. | Match the following sentences with their translations. | Semiconductors of N-Type and P-Type | Read the text again and select from the multiple choice the only solution to each problem. | Act as an interpreter. Translate the description of N-type and P-type- semiconductors given by your group mates from English into Russian. | UNIT II | Translate the following international words without a dictionary. | The P-N Junction |

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