Design and estimation of GaAsSb/InGaAs hetero-junction double-dual gate vertical tunnel FET (HJ-VTFET) biosensor

In this work, a novel Gallium Arsenide Antimonide (GaAsSb)/Indium Gallium Arsenide (InGaAs) hetero-junction double-dual gate-gate stack Vertical Tunnel FET (HJ-VTFET) biosensor is designed and its sensitivity is analyzed to detect various bio-molecules. The hetero-junction GaAsSb/ InGaAs enable high I_ON current, lower sub-threshold slope, and quick response to the bio-molecules which are mobilized in the confined cavity under the gate electrode. The effects of variation of the dielectric constant of the filled bio-molecules, cavity length, and work function of double gate on the ION, energy band diagram, and then on the sensitivity are evaluated and analyzed. For analyzing the device levels gate work function effects both neutral and charged bio-molecules are taken into consideration. It is noticed that on increasing the dielectric constant from k = 1 to k = 12, the device performance enhances and 5 orders of ON current improvement is noted. While varying the tunneling gate work function from 4.9 eV to 6.13 eV, the Ion/Ioff ratio increases in 10 orders and sensitivity of the bio-molecules varies from 0.62 to 0.74. Moreover, on increasing the positive charge density from neutral (0) to 1e15C of a fixed biomolecules in the cavity, the device ON current and sensitivity increases and it is increases by 23%.