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Explain why does conductivity of germanium crystals increase on doping with gallium?
Answers (1)
p-type semiconductor:
When germanium is doped with gallium or any other group 13 elements ,some of the positions of lattice of germanium atom are occupied by gallium. Gallium contains only 3 valence electrons. Thus the 4th valency of nearby germanium atom is not satisfied leaving this place vacant. Electron from neighbouring atom comes and fills the gap and creates a hole in its original position.
The electrons move towards positively charged plates through these under the influence of electric field for conduction of electricity. The holes appear to move towards negatively charged plates.
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