Question 4: (25 points) For a silicon pn junction at 300 K w…
Question 4: (25 points) For a silicon pn junction at 300 K with the following parameters: Na = Nd = 1×1015 cm–3, e = 1.60×10–19 C, ni = 1.5×1010 cm–3, Dn = 25 cm2/s, Dp = 10 cm2/s, and tpo = tno = 5×10–7 s. Determine: The total reverse saturation current density at 300 K. (5 points) The total reverse current is composed of the reverse current of electrons Jsn and that of holes Jsp. Determine the ratio of Jsn to Jsp, Jsn/Jsp. (6 points) All the parameters above are more difficult to control except the doping concentration. If you keep one doping concentration constant, say you keep Na constant at 1×1015 cm–3, what is the other doping concentration Nd to increase the Jsn/Jsp ratio to 3? (7 points) If you want to operate this pn junction at 400 K and keep the total reverse saturation current the same as in part (a), what would be the doping concentration if you also keep Na = Nd? ni = 2.38×1012 cm–3 at 400 K and all other parameters are independent of temperature. (7 points)