Shockley Diode Calculator

At the heart of this calculator is the Shockley ideal diode equation, which models the exponential relationship between the current flowing through a p-n junction and the voltage drop across it. The formula is expressed as:

I = I_s * (exp(V / (n * V_t)) - 1)

Where I represents the diode current, I_s is the reverse bias saturation current, V is the voltage drop across the diode, n is the emission (or ideality) coefficient, and V_t is the thermal voltage (approximately 25.85 mV at room temperature, calculated as kT/q).

Imagine you are analyzing a silicon diode operating at room temperature with a thermal voltage (V_t) of 0.026 V. Your component has a reverse saturation current (I_s) of 1e-14 Amperes and an emission coefficient (n) of 1.2. If you apply a forward voltage drop (V) of 0.7 volts, we can compute the resulting diode current.

First, divide the voltage by the product of the emission coefficient and thermal voltage: 0.7 / (1.2 * 0.026) = 22.436. Next, calculate the exponential value: exp(22.436) ≈ 5.503e9. Subtracting 1 yields essentially 5.503e9. Finally, multiply by the saturation current: 1e-14 * 5.503e9 = 0.055 Amperes, or 55 mA. Thus, under these conditions, the diode will conduct 55 milliamps of current.

Always ensure your units are consistent before running calculations—convert millivolts to volts and milliamperes to amperes where necessary. Keep in mind that the thermal voltage changes with temperature, so standard room temperature assumptions may cause slight deviations in high-heat environments. Lastly, remember that the ideal Shockley equation does not account for series bulk resistance or high-injection level effects found in extreme real-world operating states.