Question

(b) A structure that we sometimes encounter in electronic devices is a so-called p-i-n structure, consisting of a p-doped layer, an intrinsic layer and then an n-doped layer as shown in the drawing below. Assume Si as the semiconductor: n Pis. Intrinsic 5 X IOC kx10 can player Intrinsic layer n layer Majority carrier concentration Minority carrier concentration Electrical Conductivity

Answer 1

(b) in an intrinsic Semiconductor the number of electrons Ni in the conduction band is always equal to the number The holes Pi in the valence band le ni = Pi and either one of these is called the intrinsic carrier concentration. But herce a structure that is p-i-n structure. n; ²= nxP = 2x 106 x 58 10 15 = 1032 Intrin |5x105 cm ni ~ 1016 P n sid 2x1016 cm Majority Cartier Concentration Minority Carries concentration Electrical Player Intrinsic layer n layer n>P=2x1016 nap=5x105 n=P~ 1016 Pcn=sxio P>n=2x106 n=P~ 1016 eni (untap) Op= Peup op on on=neun conductivity We know Vo = ME where ue is mobility of charge carrier. Now current density due to electron Jo=ne Van where Van = ln & u. Jn = ne pe From Ohm's law Jn = on E. on repoesents the electrical conductivity of material io e on=ne un similarly Op = peup : - Total conductivity or on top = e(nunt Pup) For an intrinsic Semiconductor na Pani so, o=eni (unt Mp)