Question

Ecp 4.20P) The figure shows ban diagram of a Si PN junction diode. Before solution choose suitable values of a,b and c and show this numbers clearly in a box. a) Calculate the carrier densities plot across the junction (n=1.5 100) b)If you apply reverse bias of 1 V how the carrier densities will change across the junction ?Calculate and plot. Icev Eip- - I a ev Ecn Evp -1 beva EF Ein Eva

Answer 1

Ep Icev Eip I a el En EFF Exp I bev Ein Exu e we can see and as we know (9) From given figure figure we can Ei - Eup = 9, Eip - Evp - Koln (Na Therefore Kog Ila Na 7= hi a no du Ne a ni KT Na = exp Cat) - Na ? no exp Cart 0

6. NA= 1.5x10 to exp 0.23 to 26x103 NA = 1,5x10 10 1,5 x 10 10 exp [ 8.8462 NAS 1.042 X 10 34 / m² Similarly, b KT. No = 4,5X1070 exp 0.23 20*403 No = 1.042 XJ t uma Nos no exp H (b). Ep a cerslev Een Taev EED ofn Eup I bev Ein Ein When we applied IV reverse bias voltage, the entire band o gap will move down and getting large barrier, and diffusion becomes nearly impossible. The charge densities wy depends on the doping concentra tions which are constant as we can see from fique So when we apply 31 reverse bias tot voltage the change densities will not change across the junction.