Reverse Biased Junction Tutorial

When the battery is connected as shown, the positive terminal of the battery attracts negative electrons away from the barrier. The negative terminal attracts holes away from the barrier. The insulating barrier widens and no current flows. The junction is REVERSED BIASED.

If the reverse voltage is made high enough, then the junction will break down and electron current will flow from anode to cathode (under normal conditions, current flows from cathode to anode, when forward biased).