This is due to increased movement of the lattice and a greater frequency of collisions between the moving electrons and the lattice. Some solids are very poor conductors of electrons. Semiconductors have an energy gap between the bonding electrons and the conduction band. They do not conduct at the slightest potential difference but require a certain minimum field strength in order to overcome the energy gap between the valence band and the conduction band. Electrons promoted to the higher energy conduction band cause the semiconductor to conduct a current.
Electrons move in one direction while the positive holes move in the opposite direction.
In this case conduction is enhanced by an increase in temperature. Conduction in an electrolyte solution is similar to conduction in a semiconductor in that the current is carried in one direction by negative particles and in the other direction by positive particles. In the case of an electrolyte the charged particles are ions. Positive ions are called cations. Negative ions are called anions.