Assignment No. 1 DATE: 28/02/2012 1. Name at least two conductors 2 semiconducto

Assignment No. 1 DATE: 28/02/2012 1. Name at least two conductors 2 semiconductors and 2 insulators. 2. Explain the difference in conductors insulators and semiconductors using the energy band diagram. 3. Explain why the concentration of free electrons and holes is equal in an intrinsic semiconductor. 4. Which of the following atoms could be used as N-type impurities and which as P-type impurities? a) Phosphorous b) Antimony c) Boron d) Arsenic e) Aluminium f) Indium 5. Explain why a pentavalent impurity atom is known as donor-type impurity? 6.
Assignment No. 1 DATE: 28/02/2012 1. Name at least two conductors 2 semiconductors and 2 insulators. 2. Explain the difference in conductors insulators and semiconductors using the energy band diagram. 3. Explain why the concentration of free electrons and holes is equal in an intrinsic semiconductor. 4. Which of the following atoms could be used as N-type impurities and which as P-type impurities? a) Phosphorous b) Antimony c) Boron d) Arsenic e) Aluminium f) Indium 5. Explain why a pentavalent impurity atom is known as donor-type impurity? 6. What are the majority and minority current carriers in an N-type and a P-type semiconductor? 7. Explain what happens to the concentration of the majority carriers when the temperature of an extrinsic semiconductor is increased. 8. What process is the opposite of thermal generation of electron-hole pairs? 9. Explain what a hole is? How do they move in an intrinsic semiconductor? 10. Explain what is the need of adding an impurity to an intrinsic semiconductor? 11. Of what polarity are the impurity ions in N-type and P-type semiconductor? Justify your answer in brief.
12. Explain why at high temperature an extrinsic behaves like an intrinsic semiconductor. 13. Explain why electrons are the majority carriers in an N-type semiconductor. Date of Submission:-7th March 2012
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