A battery of e.m.f.2 volt is applied across the block of a semiconductor of length 0.1 m and area of cross section `1xx 10^(-4)m^(2)` . If the block is of intrinsic silicon at 300 K, find the magnitude of the total current. What will be the order of magnitude of total current if germanium is used instead of silicon? Given that for Si at 300K
`mu_(e)=0.135 m^(2)vV^(-1)s^(-1),mu_(h)=0.048 m^(2)V^(-1)s^(-1)`
intrinsic carrier concentration `n_(i)=1.5xx10^(16)m^(-3)`
For Ge at 300 K `mu_(e)=0.39m^(2)V^(-1)s^(-1)`
`mu_(h)=0.19m^(2)V^(-1)s^(-1),n_(1)=2.4xx10^(19)m^(-3)`

Explanation

For silicon
Total current ,I=eA `(n_(e)v_(e)+n_(h)V_(h))`
Since ,drift velocity `v_(e)=mu_(e)E` and `v_(h)=mu_(h).E`
Where `E=(V)/(l) therefore `Total current .
I=eA `(n_(e)Emu_(e)+n_(h)Emu_(h))=eA(n_(e)mu_(e)+n_(h)mu_(h))(V)/(l)`
Where `n_(1)=n_(e)=n_(h)` for intrinsic semiconductor
Substituting values for silicon :`I=8.7800xx10^(-7)A`
and for Gernanium :`I=4.46xx10^(-3)A` the magnitude of current in Ge is `10^(4)` times higher than that in Si.