Considering the influences of silicon (Si) surface potential and postannealing in oxygen ambient, a steady-state current model of double structure was proposed. For layer with different technological history, the dominated conduction mechanism for the as-deposited layer is Poole-Frenkel emission and Schottky emission for the annealed layer. The oxygen annealing treatment enhances the Schottky barrier height of interface, i.e., the higher annealing temperature, the lower , and leakage current. When the annealing temperature is, however, , the trap density starts to increase slightly because of the crystallization effect, which results in the decrease of . Using the stationary J-V model and the stretched exponential law of transient current, the charging process in layer can be described. Oxygen annealing lowers the density of trap charges and increases the decay time constant . Because of the crystallization effect in the layer annealed at temperature , decreases and increases.