Задание 2. Переведите слова и словосочетания.
Semiconductor; mobile electrons; solid material; insulator; energy level; adjacent atoms; interact; empty band; filled band; forbidden energy gap; breakdown; jump; intrinsic semiconductor; vacancy; covalent bond; hole; conduction gap; resistivity; neighbouring atom; apparent motion; outer electrons of adjacent atoms interact; to travel throughout the crystal; to gain energy from the electric field in insulators; strong external electric field; to jump the forbidden energy gap; move the conduction band through the forbidden energy gap; depend on the temperature; a few electrons in the field band can be pushed though the forbidden energy gap; appearance of a hole; acquire necessary energy; resistivity of the semiconductors decreases.
Задание 3. Переведите слова и словосочетания на английский язык.
Полупроводник; твердый материал; энергетический уровень; взаимодействовать; запрещенная энергетическая зона; пустая зона; прорыв; прыгать; ковалентная связь; дырка; проводящая зона; сопротивляемость; кажущееся движение; собственный (чистый) полупроводник; электронно-дырочная пара; прыжок валентного электрона в проводящую зону; представлять пустые энергетические уровни; проводить электрический ток свободно; больше валентных электронов приобретают необходимую энергию; запрещенная энергетическая зона узкая; двигаться в пустую зону; внешние электроны смежных атомов взаимодействуют; иметь промежуточную зону между проводящей и валентной зонами; заполненные и пустые зоны перекрещиваются; сопротивляемость полупроводника уменьшается.
Задание 4. Переведите предложения.
1. A semiconductor is a solid material. 2. In a semiconductor there is a conduction band and a valence energy band. 3. In pure (intrinsic) semiconductor materials at normal temperatures, the valence electrons are greatly bound to the atoms. 4. A semiconductor has a band gap between the conduction and valence bands. 5. Usually all the electrons are in the valence band, where they cannot conduct current. 6. However, the band gap between the conduction and valence bands is narrow. 7. When the temperature is more than absolute zero, some electrons from the valence band move to the conduction band through the forbidden energy gap. 8. Their number is very small and it depends on the temperature. Excitation (jumping) of an electron into the conduction band leaves behind a vacancy in the valence band. 9. This vacancy is known as a hole. 10. The vacancy is electrically neutral but it acts as an apparent positive charge carrier.
Задание 5. Ответьте на вопросы.
1. What is a semiconductor?
2. Does a conductor contain more mobile electrons than an insulator?
3. How many bands does a semiconductors contain?
4. What are these bands called?
5. What is there between the conduction band and a valence energy band?
6. Can we say that the conduction band is the empty band and the valence band is the filled band?
7. In what case do the electrons from the valence band move to the conduction band?
8. What is known as a hole?
9. How does a hole act?
Вариант 4
Задание 1. Переведите текст.
Extrinsic semiconductors
Pure or intrinsic semiconductors are of little use. They have an electron deficiency. Most of our modern semiconductor devices contain semiconductor materials to which certain impurities have been added to give it a predominance of either free electrons or holes. The process of adding impurities to the semiconductor is called doping. Semiconductors with foreign impurities are called extrinsic semiconductors.
The concentration of the added impurity, called dopant, is very minute, on the order of one part of impurity per ten million parts of pure semiconductor.
When an impurity material has an excess of electrons in its atoms when compared with the atoms of a pure semiconductor, this type of impurity donates electrons to the conduction band and is therefore called donor impurity. The energy levels (bands) of extra electrons are located in the vicinity of the conduction band and at a room temperature the electrons from donor levels are excited into the conduction band and are able to conduct the current.
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