Physics - Semiconductors Question with Solution | TestHub

The electric current due to the charge concentration gradient is known as diffusion current.When the charge carriers move in a semiconductor due to the applied electric field, the resulting current is known as drift current. If the positive terminal of the battery is connected to the p-type while the negative terminal of the battery is connected to the n-type, the movement of electrons is eased as they can travel to the positive terminal of the battery. This causes an increase in the diffusion current. Hence, the diffusion current is more than the drift current. So, $A$is correct

In an n-type semiconductor, the concentration of electrons is more than that of the holes. While in a p-type semiconductor, the concentration of holes is more than that of the electrons. During the formation of a p-n junction diffusion and drift are the two processes taking place. When a p-n junction is formed, holes diffuse from the p-side to the n-side while electrons diffuse from the n-side to the p-side. This result due to the concentration gradient across p and n sides, which gives rise to a diffusion current across the junction. The diffusion results in an electric field from p-side to n-side. Thus, $R$ is incorrect as diffusion current in $p-n$ junction is from $p$ side to $n$-side.