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Explain why does conductivity of germanium crystals increase on doping with gallium. |
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Answer» Solution :On doping germanium with gallium some of the positions of lattice of germanium are occupied by gallium. Gallium atoms has only three valance electrons that are used up on normal COVALENT band. HENCE for one gallium atoms, one hole is created at a missing site of fourth electron which are responsible for CONDUCTION. Electron from neighbouring atoms come and fill the hole. Under the influence of electric field electrons move TOWARDS POSITIVELY charged plates through these holes and conduct electricity. Holes move towards negatively charged plates. |
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