When a p-n junction diode is reverse biased, then

In reverse biasing, the applied voltage V on the r_side is positive and is negative on the p-side. The applied bias V and the barrier potential ${\mathrm{V}}_{\mathrm{B}}$ are in the same direction making the effective function potential V - ${\mathrm{V}}_{\mathrm{B}}$. As a result, the junction width will increase. The higher junction potential would restrict the flow of majority carriers to a much greater extent. However,
such a field will favour the flow of minority carriers. So, reverse bias current will be due to the minority carriers only.