1.

The number of silicon atoms per m^(3) is 5xx10^(28). This is doped simultaneously with 5xx10^(22) atoms per m^(3) of Arsenic and 5xx10^(20) per m^(3) atoms of Indium. Calculate the number of electrons and holes. Given that n_(i)=1.5xx10^(16)m^(-3). Is the material n-type or p-type?

Answer»

SOLUTION :Here number of atoms of Arsenic per `m^(3)` is,
`N_(D)=5xx10^(22)`
and number of atoms of Indium per `m^(3)` is,
`N_(A)=5xx10^(20)`
`therefore` Number of electrons per `m^(3)`,
`n_(e )=N_(D)-N_(A)=(5xx10^(22)-0.05xx10^(22))`
`=4.95xx10^(22)`
but `n_(i)^(2)=n_(e )n_(h)`
`therefore n_(h)=(n_(i)^(2))/(n_(e ))=((1.5xx10^(16))^(2))/(4.95xx10^(22))`
`thereforen_(h)=0.4545xx10^(10)`
`~~0.45xx10^(10)`
`~~4.5xx10^(9)m^(-3)`
Here `n_(e ) GT gt n_(h)` so semiconductor is n-type.


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