A-LevelPhysicsQuantum physics9702/41 · Oct/Nov 2018 · Q105 Marks
Some of the electron energy bands in a semiconductor material at the absolute zero of temperature are shown in [Figure 10.1]. Use band theory to explain why, as the temperature of the semiconductor material rises, the electrical resistance of the sample of material decreases.
- Use band theory to explain why, as the temperature of the semiconductor material rises, the electrical resistance of the sample of material decreases.[5]
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Mark scheme
Marking points from the official mark scheme (Oct/Nov 2018). The mark or mark type is shown in brackets.
- [B5] Any five points from: • as temperature rises electrons gain energy • electrons enter conduction band • (positively charged) holes left in valence band • more charge carriers (so resistance decreases) • (as temperature rises,) lattice vibrations increase • effect of increase in number of electrons or holes or charge carriers outweighs effect of increased lattice vibrations (so resistance decreases)
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