Question
Physics Question on Semiconductor electronics: materials, devices and simple circuits
In a pure semiconductor crystal, if current flows due to breakage of crystal bonds, then the semiconductor, is called
A
donor
B
acceptor
C
intrinsic semi-conductor
D
extrinsic semi-conductor
Answer
intrinsic semi-conductor
Explanation
Solution
In the case of an intrinsic semiconductor (say Si) where each Si is having 4 outermost electrons, its crystal structure consists of making 4 covalent bonds with 4 negihbouring Si atoms. Each bond consists of two eletrons. 
Now if one of the bonds get broken due to some reason (collisions or high temperature) then one electron gets freed and it will be having sufficient energy to cross the band gap and be ready for conduction. So in intrinsic semiconductors, current flows due to breakage of crystal bonds.