The last feature is of particular importance since under such magnitudes of electric field, generation of hot electrons process takes place [56, 58]. Under a very high field,electrons are injected over the potential barrier into the positively biased depletion region. The strong electric field easily accelerates the particles to attain high kinetic energy. Minority carriers (holes) are then created by impact ionisation and are swept towards the interface. As a result, the barrier height is lowered which increases the current sharply. Further increase of current is obtained if recombination of the swept holes with trapped electrons at the interface is considered.