I am reading Neaman's book on semiconductor physics and devices and one of the more important conclusions are that excess holes and electrons drift and diffuse together due to internal electric fields. However, when holes and electrons move in the same direction, wouldn't that mean zero net current? Additionally, if this is true, why would the electrons/holes move at all if the result in terms of current is the same.
I find it very hard to grasp why the electrons and holes move in the same direction. As the external field tries to separate the electrons from the holes, doesn't the internal electric field get weaker as the electrons move further away from the holes? And wouldn't the internal field be formed locally in the semiconductor, near the excess carriers, resulting in the external field to be dominating in most location in the lattice? This would cause the carriers to separate in the end. However, Neaman's explanation indicates otherwise.
Thanks in advance