- •Unit 11. The Forward-Biased p-n Junction Language Work
- •Match the English sentences with their Russian equivalents. Define the forms of participles (Present/Past/Perfect/Active/Passive).
- •Translate the following sentences paying attention to Participle I.
- •Translate the following sentences paying attention to the ways of translation of –ing-forms.
- •Translate paying attention to the ways of translation of -ed-forms.
- •Change the complex sentences given below according to the examples and translate them into Russian:
- •Choose the sentences with Participle I from the ones given below and translate them:
- •Analyse the following examples and translate them.
- •Read and translate the following international words paying attention to suffixes and prefixes:
- •Fill in the table
- •Read the following words. What Russian words with analogue meaning do they resemble?
- •Starting from the second component
- •Read and translate
- •Translate the following word-combinations. Compare the word-order in English with that in Russian:
- •Match the following sentences with their translation:
- •Choose a correct modal verb
- •Specialist Reading
- •Read the text “The Forward-Biased p-n Junction” only once. How much can you remember? Answer these questions without additional reading.
- •If you failed try to answer these questions again after doing the exercises given below the text.
- •Study the text and translate the following:
- •Say word-combinations in bold in turn. Each next student repeats the word-combinations of the previous ones. The last student repeats everything.
- •Insert the following words in the gaps in the text below.
- •Speaking
- •In Russian write a content-based summary of the text you have translated.
- •Make a reverse written translation (from Russian into English) of your summary.
- •Find more information about different types of junctions and tell your group mates.
Say word-combinations in bold in turn. Each next student repeats the word-combinations of the previous ones. The last student repeats everything.
Insert the following words in the gaps in the text below.
If a battery is connected … in the direction shown in the figure below, holes are … the positive end of the crystal and are … the junction; and electrons are repelled from the negative end of the crystal and also drift towards the junction. This … and electrons … the junction reduces both the … the depletion layer and the … the potential barrier, and the … is said to be forward biased. … 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…, there is a net majority charge carrier … across the junction from the P-type region to the N-type region. This current increases very rapidly with … in the forward … voltage.
The holes drifting through the P-tуре region towards the P-N junction may be considered to have been … by the positive terminal of the battery. Some of these holes may … with electrons diffusing across the junction in the other direction and so the hole current across the junction is slightly less than the injected hole current. After they have passed across the junction the holes recombine with the … 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 … the crystal. The current … the P-type region as a hole current and … the N-type region as an electron current.
Choose some sentences from the text and transform them using Predicative Constructions with Participles.
For example: If a battery is connected across the crystal, holes are repelled from the positive end of the crystal and are caused to drift towards the junction. – A battery having been connected across the crystal, holes are repelled from the positive end of the crystal and are caused to drift towards the junction.
Speaking
Summarize the text “The Forward-Biased P-N Junction” in 150 words using at least 4 cases of Predicative Constructions with Participles.
Act as an interpreter.
Translate the summary given by your group-mates from English into Russian.
Give a reverse translation of the summary (from Russian into English).
Translate the text “Reverse Biase” with a dictionary in writing paying attention to the use of Participial Constructions.
The term “reverse biased” is considered to be referred to how a diode is used in a circuit. A diode being reverse biased, the voltage at the cathode is higher than that at the anode. Therefore, no current will flow until the diode breaks down. Connecting the P-type region to the negative terminal of the battery and the N-type region to the positive terminal corresponds to reverse bias.
The P-type material having being connected to the negative terminal of the power supply, the 'holes' in the P-type material are pulled away from the junction, causing the width of the depletion zone to increase. Similarly, the N-type region being connected to the positive terminal, the electrons will also be pulled away from the junction. Therefore we see the depletion region widening, and it does so increasingly with increasing reverse-bias voltage. This increases the voltage barrier causing a high resistance to the flow of charge carriers thus allowing minimal electric current to cross the p–n junction.
The strength of the depletion zone electric field increased, the reverse-bias voltage increases. Once the electric field intensity increases beyond a critical level, the p–n junction depletion zone breaks-down and current begins to flow, usually by either the Zener or avalanche breakdown processes. Both of these breakdown processes are non-destructive and are reversible, as long as the amount of current flowing does not reach levels that cause the semiconductor material to overheat and cause thermal damage.
This effect is used to one's advantage in Zener diode regulator circuits. Zener diodes have a certain - low - breakdown voltage. A standard value for breakdown voltage is for instance 5.6V. This means that the voltage at the cathode can never be more than 5.6V higher than the voltage at the anode, because the diode will break down - and therefore conduct - if the voltage gets any higher. This effectively regulates the voltage over the diode.
Another application where reverse biased diodes are used is in Varicap diodes. The width of the depletion zone of any diode changes with voltage applied. This varies the capacitance of the diode.