Shockley Diode Calculator

An ideal diode allows current to flow in only one direction with zero voltage drop and infinite resistance in reverse. Real diodes have a forward voltage drop (typically 0.7V for silicon), finite reverse resistance, and follow the Shockley equation more closely.

The Shockley equation is I = Is(e^(VD/nVT) - 1), where I is current, Is is saturation current, VD is diode voltage, n is emission coefficient, and VT is thermal voltage. It describes the current-voltage relationship in PN junction diodes.

The emission coefficient or ideality factor typically ranges from 1.0 to 2.0. For an ideal diode, n = 1.0. Real diodes have higher values due to recombination effects and manufacturing variations.

Thermal voltage VT = kT/q, where k is Boltzmann constant, T is temperature, and q is electron charge. At room temperature (25°C), VT ≈ 26mV. It increases with temperature at about 2mV per degree Celsius.

Forward bias occurs when VD > 0 (anode positive relative to cathode), allowing significant current flow. Reverse bias occurs when VD < 0, resulting in minimal current flow (only saturation current).

Saturation current is the small reverse current that flows when the diode is reverse biased. It's typically in picoamperes or nanoamperes and depends on diode geometry, doping, and temperature.

In reverse bias, the exponential term becomes very small, so current approaches the negative saturation current (-Is). This is normal behavior - diodes are designed to block reverse current flow.

Temperature increases both thermal voltage (VT) and saturation current (Is). Higher temperature reduces forward voltage drop and increases reverse current, making the diode less ideal.