Question:
Suppose a ‘n’-type wafer is created by doping Si crystal having 5 × 1028 atoms/m3 with 1ppm concentration of As. On the surface 200 ppm Boron is added to
create the ‘P’ region in this wafer. Considering ni = 1.5 × 1016 m–3,
(i) Calculate the densities of the charge carriers in the n & p regions.
(ii) Comment which charge carriers would contribute largely for the reverse saturation current when the diode is reverse biased.
Solution:
(i) Ne = 5 × 1022 m3
Nh = 0.45 × 1010 m3
Nh = Na = 1 × 1025 m3
Ne = 2.25 × 107 m3
(ii) The minority carrier holes of n-region would contribute largely for the reverse saturation current when the diode is reverse biased.