Question

difference between diffusion current and drift current in pn junction

Answer 1

Diffusion current occurs even though there isn't an electric field applied to the semiconductor
Drift current depends on the electric field applied on the p-n junction diode.
Diffusion current depends on constants Dp and Dn, and +q and −q, for holes and electrons respectively but it is independent of permittivity
Drift current depends upon permittivity.
Direction of the diffusion current depends on the change in the carrier concentrations, not the concentrations themselves.
Direction of the drift current depends on the polarity of the applied field.