When p-n junction is reversed biased, the positive terminal of the external battery is connected to n-side of p-n junction and its negative terminal to p-side of p-n junction. The positive terminal of the external battery attracts the majority carrier electrons from the n-region and its negative terminal attract the majority carrier holes from p-region. Due to it, the majority charge carriers move away from the junction. This increases the width of the depletion layer.
