Role of trap states in the insulator region for MIM characteristics

A theoretical study of the trap-assisted charge injection in a blocking contact metal-insulator-metal (MIM) structure is made. In this mechanism a charge first tunnels to the vacant trap states in the insulator and is subsequently thermally excited or is tunneled to the conduction band of the insulator. A comparison is made between different contact current mechanisms for such sturctures and it is found that this mechanism is very important for the insulators containing trap states of the order of 1018 cm−3 and more, at low contact voltages. Finally we compare the current-voltage characteristics of various devices containing different density of trap states in the insulator region, with reference to the present theory. We find that the I-V characteristics of solid-state devices strongly depend on the trap density of the insulator region near the cathode