Investigation into gate-to-source capacitance induced by highly efficient band-to-band tunneling in p-channel Ge epitaxial tunnel layer tunnel FET

The gate-to-source capacitance (C_GS) in the p-channel tunnel FET (pTFET) with a Ge epitaxial tunnel layer (ETL) structure is investigated. The characteristic of C_GS is revealed and studied with various frequencies and temperatures. Due to the highly efficient band-to-band tunneling (BTBT) in the Ge ETL pTFET, the minority carriers for the source can be generated by the BTBT process and can respond with the gate voltage. Therefore, the contribution of C_GS to the total gate capacitance in the ON-state would increase, which results in a decrease of the gate-to-drain capacitance. This property is beneficial to the suppression of the Miller capacitance effect on the TFET-based circuit.