Diffusion current
= Diffusion current
A <diffusion current> results from a spatial <carrier density> gradient. For semiconductor electrons and holes in one dimension, conventional-current densities are $J_n=eD_n\,dn/dx$ and $J_p=-eD_p\,dp/dx$. Their different signs reflect negative and positive carrier charge. At equilibrium each species' <diffusion current> is balanced by its <drift current>, giving zero net current while the individual transport contributions need not vanish.