The zero-biased junction capacitance of a silicon pn junction is \(C_{j o}=0.4 \mathrm{pF}\). The doping concentrations are \(N_{a}=1.5 \times 10^{16} \mathrm{~cm}^{-3}\) and \(N_{d}=4 \times 10^{15} \mathrm{~cm}^{-3}\). Determine the junction capacitance at

(a) \(V_{R}=1 \mathrm{~V}\),

(b) \(V_{R}=3 \mathrm{~V}\), and

(c) \(V_{R}=5 \mathrm{~V}\).