Given, number of silicon atom, nSi=5×1028 atoms ∕m3 Number of arsenic atom, nAs=4.5×1021atom∕m3 ni=1.5×1016∕m3 Number of free electrons obtained from doping =ne=nAs=4.5×1021 electrons ∕m3 ∴ Total number of electrons after doping, N=ne+ni=4.5×1021+1.5×1016 =1.5×1016(3×105+1] =1.5×1016(3×105)=4.5×1021 According to mass-action law, ne⋅mh=ni2