Present Perfect Active (I have patented)

Affirmative

For example:

· Scientists and engineers have recently developed and introduced a whole range of important inventions.

· Look! A hole has appeared at point A.

Negative

For example:

· We haven’t received perfect results in these tests.

· The inventor hasn’t introduced his innovation yet.

Questions

For example:

· Has an electron freed itself yet?

Present Perfect Passive (measurements have been done)

Affirmative

For example:

· A synthetic diamond has already been created in the laboratory by Belarusian scientists.

Negative

For example:

· Unfortunately some technical devices haven’t been patented yet.

Questions

For example:

· Has hadron collider been started?

· Have covalent bonds been broken?

1. Fill in the table.

2. Fill in the gaps using the following verbs: break, free, move, come, occur, appear.

Fig. 1. A hole has appeared at point A	- Figure 1 shows a part of a silicon crystal in which the breaking of covalent bonds is taking place. - Was this caused by heating? - Yes, by heating. In Figure 1 it is shown that one covalent bond … and an electron … itself. A hole … at point A.
- Will you be able to explain what is taking place in the next figure (Fig. 2)? - Yes, of course. A hole … at point B and now two electrons can move through the crystal.	Fig.2. A hole has appeared at point B.
Fig. 3. Hole A has disappeared and hole C has appeared	- Look at Fig. 3. The second electron … close enough to the first hole and is attracted by its electric field. Recombination … . Now there is no hole already at point A. But still there is a hole at point B. It seems that the hple… from position A to position B. - Looking at this figure, it becomes clear that one more hole … at point C.
- As shown in Fig.4 the third free electron … through the crystal lattice. Again recombination … and a hole … . The effect is as though a hole … from point A to point C.	Fig. 4. Hole B has disappeared

3. Make up sentences using Present Perfect. Use the prompts in brackets. Mind the position of just/already/yet.

For example:

How have you decreased the capacitance of your system?

I have just connected equal capacitors in series.

(I/just/connect/equal/capacitors/in series)

1. Can we observe any changes in the movement of electrons and holes?

Of course, we can, but …

(only/when/process/of recombination/already/occur)

2. Could you stop the movement of holes quite fast?

No, …

(I/just/heat/a peace of silicon)

3. Have you already changed the random character of the movement of holes in a piece of germanium?

Unfortunately …

(I/not/apply/any/voltage/yet)

4. Do you consider me an expert in the problem of the movement of holes?

No, …

(I/already/consider/a lot of/important/things/but not all)

5. Could you increase the amplification factor of our circuit?

Yes, …

(I/already/replace/a triode/for a tetrode)

4. Open the brackets and complete the dialogues with just, already, yet. Use Passive Voice where nessesary.

1. A: How do we call the phenomenon of attracting an electron by electric field?

B: Don’t you know that the scientists … (call) this process recombination?

2. A: I learned about the intrinsic conduction yesterday .

B: Yes, but you … (not/consider) in what types of materials it takes place.

3. A: Do we have a method to divide the flow of electrons and holes?

B: I … (do) this by means of applying voltage.

4. A: There is no sense to look for different ways of controlling the increase of temperature in a triode. How do you think, why?

B: I think, because a termometer scale … (invent).

5. You are asking students questions about things they have done. Make questions with ever using the words in brackets.

For example:

(know/physicist?) Have you ever known a famous physicist personally?

1. (observe/phenomenon of recombination?)

2. (miss/lectures?)

3. (design/project?)

4. (introduce/invention?)

5. (take part/scientific conference?)

6. Complete the sentences using today/this year/this month etc. + Present Perfect.

For example: There was a relatively high rate of recombination in the prototype yesterday, but it hasn’t recovered the old level today.

1. Some centuries ago scientists didn’t have enough information about the nature of intrinsic conduction, but … .

2. The invention of hydrogen and nuclear bombs in the XX century made people all over the world be afraid for their lives, but due to common efforts of politicians ….

3. After the Stone Age of B.C. era we all observe the phenomenon of global warming, which ….

4. The plant “Horizont” had a severe setback in production in the beginning of the nineties, but … .

5. In 1975 our faculty wasn’t able to trainprepare experts in the sphere of aero space technologies, but … .

7. Read the situations and write sentences using the example.

For example:

John is working with the Internet Explorer at the moment and looks like a novice in this business.

You: Have you ever worked with the Internet Explorer?

John: No, but I’ve already learnt the most important rules about this program.

1. Ann is trying to take the temperature of the device with the help of a Centigrade thermometer. But she is using it in a wrong way.

You:

Ann:

2. Peter starts putting on a spacesuit for working in the open space. But it seems to you, that he has forgotten some important parts of the suit.

You:

Peter:

3. Greg wants to observe the constellation of Orion, but can’t adapt the telescope.

You:

Greg:

4. Alexandra got the task to increase the conductivity of a piece of germanium. She cooled it.

You:

Alexandra:

8. Rewrite these sentences into Passive Voice.

1. The Germans have recently integrated chips with all important biometrical data in the passports of citizens.

2. Japanese scientists have just presented a few generations of robot-humanoid in Tokyo and other technological centers of this country.

3. The fans are furious. FIFA hasn’t introduced the technology based on chips integrated into a ball and sensors into a gate.

4. Real games haven’t fully exchanged tetris for another game.

5. Mobile operator Life has already introduced 3G Internet technology.

9. Make sentences from the words in brackets using the Present Perfect Passive.

1. I have always wanted to travel through time. (But/time/machines/not/invent/yet).

2. We are looking for the place to see some interesting events. (Minsk-Arena/build/as a/high-technology/complex/to/hold/the/competitions/

and/concerts/of/world/level).

3. Not only tests help us to obtain objective results. (This/theory/also/use/for/analyzing/the/experimental/data).

4. Today’s mobile connection looks fantastic. (Many/different/devices/create/in/order/to/improve/the/performance/of/communications).

5. Physicists think that Newton’s laws are the main laws of nature, but chemists object that …

(Mendeleev’s/periodic/law/accept/as/a/universal/law/of/nature).

10. Form adjectives from the following nouns using the suffix -ous and translate them.

For example: advantage – преимущество;

advantageous – преимущественный.

Analog, danger, oxygen, hydrogen, phosphorus, cobalt.

11. Read and translate word-combinations.

A.start from the first component

B.start from the second component

12. Match the following sentences with their translations.

13. Answer the following questions using the verbs: write, use, design, interest, experiment, read.

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

For example: Both electrons and holes are charge carriers.

SPECIALIST READING

15. Read the text “The Movement of Holes”. Mark the following sentences as true (T) or false (F).

1. In figure 1 of exercise 2 we see that one covalent bond has broken, one electron has freed itself, and a hole has disappeared at point A.

2. The movement of electrons and holes is random.

3. A great number of electrons have freed themselves.

4. The hole has changed its position.

5. Conduction may take place in a pure semiconductor.

6. If some voltage is applied, the electrons begin to move in one direction and the holes begin to move in the opposite direction.

7. The increase of temperature of the semiconductor doesn’t increase its conductivity.

The Movement of Holes

If a silicon crystal is heated, the breaking of covalent bonds is taking place. Figures of exercise 2 in Unit 7 show what occurs in the atoms of the crystal. In one figure we see that one covalent bond has broken, one electron has freed itself, and a hole has appeared at point A. In the next figure we see that a second hole at point B has appeared. Now there are two free electrons. The second electron is passing the first hole. It has been attracted by the hole and there is no hole at point A. It seems that the hole has moved from position A to position B.

Then we see that the third electron has freed itself and recombination has taken place at some other point where the hole has disappeared.

The movement of electrons and holes is random.

But if some voltage is applied, then the electrons begin to move in one direction and the holes begin to move in the opposite direction. Thus, conduction may take place in a pure semiconductor. Such a conduction is known as intrinsic conduction. The increase of temperature of the semiconductor increases its conductivity.

16. Read the text again and complete the sentences with the correct ending.

1. If a silicon crystal is heated, …

2. As a result of breaking of one covalent bond, one electron …

3. The second electron is passing the first hole and it …

4. The third electron has freed itself and …

5. If some voltage is applied …

6. The conduction which takes place in a pure semiconductor is known as …

7. The increase of temperature of the semiconductor …

17. Work in pairs. Ask your partner some questions based on the text. Make sure you use the correct auxiliary verb.

For example:

The breaking of covalent bonds takes place (Where?)

Where does the breaking of covalent bonds take place?

1. In one figure we see that one covalent bond has broken (What …?) – …

2. If some voltage is applied, then the electrons begin to move (How?) – …

3. The increase of temperature changes the features of a semiconductor (How?) – …

4. Conduction may take place in (Where?) – …

SPEAKING

18. Summarize the text “The Movement of Holes” in 100 words using the figures of exercise 2:

19. Describe the process of recombination to your group mate using active terms of the Unit and the Present Perfect

20. Try to work as an interpreter. Translate the explanation of the way the electron frees itself given by your group mates from Russian into English.

21. Translate the text, which contains additional information about electron-hole movement with a dictionary in writing. Pay attention to the new words and the use of the Present Perfect.

Measuring the Movement of Holes in Crystal Surfaces

Vacancies in crystal surfaces are holes where atoms are missing from otherwise regular and uniform crystal lattices. Scientists have suspected for some time that vacancies are responsible for motion in crystals.

This motion occurs as the holes trade places with atoms, leading to atom-sized bubbles that percolate across crystal facets.

Now, researchers at the University of Leiden in the Netherlands have managed to measure vacancy motion in a copper crystal, and they have found that the holes are surprisingly mobile.

The discovery has important implications for the semiconductor industry and technologies that rely on tiny surface structures that may be gradually destroyed through vacancy mediated motion.

The researchers used a scanning tunneling microscope (STM) to study vacancy motion by monitoring the positions of indium atoms embedded in a copper lattice.

As vacancies move rapidly, changing places with atoms roughly a hundred million times each second at room temperature, comparatively slow STMs cannot image vacancies directly. Instead, the researchers calculated vacancy motion by tracking the positions of the indium atoms.

From one image to another, indium atoms exhibited long jumps which result from multiple vacancy interactions. Essentially, the indium atoms move across the copper crystal in much the same way that individual pieces may be maneuvered from one place to another in toys known as slide puzzles.

Although high vacancy mobility may be bad news for manufacturers of microstructures, the new insights will potentially help to optimize crystal growing procedures vital to the semiconductor industry.

In future work, the researchers plan to create vacancies artificially by selectively removing atoms from a chilled crystal surface. Provided that crystal is sufficiently cooled, the vacancies should move slowly enough to show up in STM images.

22. In Russian write a content-based summary of the text you have translated.

23. Make a reverse written translation (from Russian into English) of the text “Measuring the Movement of Holes in Crystal Surfaces”.

24. Find more information about the movement of holes and tell your groupmates.

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