Silicon is doped with 5 times 1016 arsenic atomscm3 a Is the

Silicon is doped with 5 times 10^16 arsenic atoms/cm^3. (a) Is the material n- or p-type? (b) Calculate the electron and hole concentrations at T= 300K.

Solution

(a) Arsenic is pentavalent atom.it has five valence electrons in which 4 electrons forms covalent bonds with 4 silicon atoms. so it has one free electron. so this is n-type semiconductor.

(b) No of electrons=No of donor atoms(n type)

electron concentration, n=ND=5*10^16

p=ni^2/n;intrinsic concentration for silicon 300k,ni= 1.45*10^10

hole concentration, p=(1.45*10^10)^2/(5*10^16)=4205 /cm³