A silicon diode operating at 25 °C has a reverse saturation current $I_s=1\times 10^{-15},\text{A}$ and an ideality factor $n=1$. Find the forward current when a voltage of $0.8,\text{V}$ is applied. Use the Shockley diode equation $I=I_s[exp(V/(n{V}_T))-1]$ and take the thermal voltage $V_T=25.85,\text{mV}$.

Step-by-step solution

1. 1. Compute the exponent: $V/(n{V}_T)=0.8/(1\times 0.02585)=30.95$.
2. 2. Compute the exponential: $exp(30.95)\approx 1.88\times 10^{13}$.
3. 3. Apply the Shockley equation: $I=1\times 10^{-15},\text{A},\times (1.88\times 10^{13}-1)\approx 1\times 10^{-15},\text{A}\times 1.88\times 10^{13}$.
4. 4. Multiply: $I\approx 1.88\times 10^{-2},\text{A}=0.0188,\text{A}$.
5. 5. Re‑check arithmetic: Using more precise value $exp(30.95)=1.79\times 10^{13}$ gives $Iapprox1.79\times 10^{-2},\text{A}$.
6. 6. Final answer: $Iapprox1.8\times 10^{-2},\text{A}$.

Concept tested: Shockley diode equation

Published 5 September 2026 · Last updated 16 September 2026 · How this solution was prepared and checked