Question

The transition capacitance, CT of a PN junction having uniform doping in both sides, varies with junction voltage as  ________

(a) (VB )^1/2

(b) (VB )^-1/2

(c) (VB )^1/4

(d) (VB )^-1/4

This question was addressed to me in final exam.

Query is from Diode Capacitances topic in portion Semiconductor-Diode Characteristics of Electronic Devices & Circuits

Answer 1

Right choice is (b) (VB )^-1/2

Explanation: CT = K/(V0+VB)^1/2

As it’s having uniform doping on both sides, the voltage V0 will be zero. So, CT=K/(VB)^1/2. The variation of transition capacitance with built in capacitance is (VB )^-1/2.