CDS 2017 PYQ with Answer — When a piece of pure silicon is doped with aluminium, then

2017 · Q8

When a piece of pure silicon is doped with aluminium, then

General KnowledgePhysics

Athe conductivity of the doped silicon piece will remain the same.
Bthe doped silicon piece will become n-type.
Cthe doped silicon piece will become p-type.
Dthe resistivity of the doped silicon piece will increase.

Explanation

Aluminium is trivalent (group 13); doping tetravalent silicon with it creates acceptor sites and mobile holes, yielding a p-type semiconductor. Pentavalent dopants such as phosphorus give n-type material. Hence C.