of P 3 at x 3 ¼ Æ L which in this specific example are not considered because for a PN
junction the electric field, electric displacement, and polarization vanish sufficiently
far away from the junction [3]. (d) and (e) of Fig. 3.5 show clearly that a PN junction
has formed with a typical built-in electric field and a built-in potential. As λ
increases, all fields change more rapidly as expected.
Fig. 3.5 Effects of λ. (a) Doping and mobile charge ρ
e /q. (b) Polarization charge ρ
P
/q. (c) Total
charge (ρ
e + ρ
P )/q. (d) Electric field E 3 (x 3 ). (e) Electric potential φ(x 3 )
3.4 Smoothly Graded PN Junction
43
junction the electric field, electric displacement, and polarization vanish sufficiently
far away from the junction [3]. (d) and (e) of Fig. 3.5 show clearly that a PN junction
has formed with a typical built-in electric field and a built-in potential. As λ
increases, all fields change more rapidly as expected.
Fig. 3.5 Effects of λ. (a) Doping and mobile charge ρ
e /q. (b) Polarization charge ρ
P
/q. (c) Total
charge (ρ
e + ρ
P )/q. (d) Electric field E 3 (x 3 ). (e) Electric potential φ(x 3 )
3.4 Smoothly Graded PN Junction
43