Final answer:
When a p-n junction is reverse-biased, the depletion layer width and barrier potential both increase, resulting in a significant reduction in current flow.
Step-by-step explanation:
When a reverse bias is applied to a p-n junction, it means that the positive terminal of the battery is connected to the n-type material and the negative terminal is connected to the p-type material.
This configuration results in a widening of the depletion layer because the external electric field opposes the diffusion of charge carriers, thereby increasing the region in which there are no free carriers.
As the depletion layer widens, the barrier potential or potential energy difference across the p-n junction also increases, which makes it more difficult for the charge carriers to cross the junction, thus significantly reducing the current flow through the diode.
In contrast, if the diode were in a forward bias situation, the positive terminal would be connected to the p-type side, leading to a narrowing of the depletion layer, a decrease in the barrier potential, and allowing current to flow more easily across the junction.