Built-In Voltage Sets Barrier Energy - Semiconductor Physics: Bands, Doping, and Junctions Step by Step

A toy junction barrier is energy per charge. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Built-in voltage sets an effective barrier voltage

With no applied voltage, the effective toy barrier voltage is 3 volts.

V_{\mathrm{eff}}=3\ \mathrm{V}

Energy per charge gives the barrier energy

Charge 2 coulombs times 3 volts gives 6 joules.

E=qV=2\cdot 3=6\ \mathrm{J}