Band Theory WS

Band Theory WS - 5. Which picture above best illustrates...

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Worksheet on Bonding in Solids 1. Identify each of the following band structures as belonging to either a conductor, semiconductor or insulator. In each structure, label the valence and conduction bands, the band gap, and give representative values of the band gap for each. a) b) c) E 2. A compound has the following band diagram, with the shading representing occupancy by electrons. This solid has a completely filled lower energy band and a partially filled higher energy band. The energy gap between the two bands is equivalent to 2.2 eV. a. Predict the electrical properties of this solid on the basis of its band diagram. That is, would you expect it to be a conductor, a semiconductor or an insulator? Explain your answer. b. What would happen to the electrical properties of this compound if all of the electrons were removed only from the conduction band? Why?
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1.66 eV e - e - e - e - e - e - 5.2 eV 1 2 3 4 5 3. Which picture above best illustrates the band structure for a p-type semiconductor? 4. Which picture above best illustrates the band structure for a pn junction?
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Unformatted text preview: 5. Which picture above best illustrates the band structure for an n-type semiconductor? 6. Which picture above best illustrates the band structure for an insulator? 7. If you had a semiconductor made of Al and P, what would you substitute for the P to decrease the band gap? 8. To promote electrons from the valence band to the conduction band, what voltage (in V) must be applied to a 2.35 cm thick sample of the semiconductor with the band gap of 2315 kJ/mol? 9. What wavelength of light will be sufficient to move electrons across the band gap in ZnS? Is this visible light? GIVEN: E g for ZnS = 2.34 eV. 10. What temperature in degrees K must you raise ZnS to in order to move electrons across the gap thermally? 11. Indium arsenide, InAs, has a band gap energy of 0.35 eV. To make a compound semiconductor with a larger band gap you could substitute which element for As ? (a) In (b) P (c) Sb (d) Zn 12....
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This note was uploaded on 06/15/2010 for the course CHEM 124 taught by Professor Hascall during the Winter '08 term at Cal Poly.

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Band Theory WS - 5. Which picture above best illustrates...

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