Effects of Energy Band Gap Traps on Drain Current in Tunneling Field Effect Transistors

In this paper the impact of the trap assisted tunneling mechanism on the subthreshold characteristics of the tunneling field effect transistors is investigated. It is shown that the trap assisted tunneling is the dominant charge transfer mechanism before the band to band tunneling starts. Employing a modified SRH formalism, we show that, at the room temperature and for the subthreshold voltages, the trap assisted tunneling current always dominates and degrades the switching characteristics of the device which is measured by the subthreshold swing. This approach is applicable to the double gate and the gate-all-around structures where the traps are located in the source-channel tunneling junction. The trap assisted tunneling strongly depends on the electric field and the temperature. The considered transistors in this research are based on the compound semiconductors of groups three and five of periodic table. The effects of various structural parameters and material systems on the trap assisted tunneling current are studied, too.