Design and Investigation of Gate Overlap Step Shape Double Gate (SSDG) TFET for Photosensing Applications

This work examines the optical properties of Gate Overlap Step Shape Double Gate Tunnel Field Effect Transistor (GO-SSDG-TFET) based photosensor in the visible spectrum range at wavelengths (λ = 300–700 nm). We have presented a comparative study of Ge source GO-SSDG-TFET with the conventional Si source TFET at constant intensity (I) of 0.7 W/cm² for three distinct λ = 300, 500, and 700 nm. We have extracted the drain current, electron density, and energy band diagram for these photosensor at different λ. Moreover, the optical parameters like sensitivity (S_n), Signal to Noise Ratio (SNR), responsivity (R) and quantum efficiency (η) are reported for the considered photo sensors. Both the photosensor reports excellent optical features because of its huge absorption and emission rates, which is a result of the high incoming optical energy (E_g) at λ = 300 nm. Moreover, the optical properties of Ge-GO-SSDG-TFET is superior than Si based photosensor. The obtained values of sensitivity, SNR, and responsivity are 86.2, 72.5 dB, and 0.71 A/Watt, respectively, at λ = 300 nm for Ge-GO-SSDG-TFET. Finally, a tabular summary of optical parameters between a suggested TFET-based photosensor with the photosensor mentioned in the literature is presented.