# Arsen dopant concentration in Si

What is the concentration achieved when 1 gram of As is added to 1 $m^3$ of silicon?

Molecular mass of As is $M(As) =75$ grams

75 grams As have…..$N_a =6.023*10^{23}$ atoms

1 gram of As have…..x atoms

$x =6*10^{23}/75= 8*10^{21} atoms/m^3$

Each As atom give one electron. hence the electron concentration is

$n =8*10^{21} m^{-3}$

holes concentration is the intrinsic Si concentration

$p =1.5*10^{16} m^{-3}$