Photosensor Based on Split Gate TMD TFET Using Photogating Effect for Visible Light Detection

This paper reports a highly-sensitive and low power photosensor based on split gate tunnel field effect transistor (TFET) structure for visible light detection in wavelength ranging from 450-750 nm. The TFET based sensing device utilizes the photogating effect in a portion of transition metal dichalcogenide (TMD) channel. The optically tunable workfunction contrast between the two gates of dual material gate (DMG) TFET achieves significant gains in the overall device characteristics. It demonstrates high photo-to-dark current ratio of the order of 10⁸ and variation in responsivity in the range between 10³AmW^-1 to 10^-5AmW^-1 for V_gs = -0.9 V. This paper further discusses the photodetector performance based on the position of the photogate on the tunneling or auxiliary side, the gate splitting ratio between the photosensing region and the metal, and the n-TFET based device design. The device performance has been analyzed using the analytical model for the optically controlled workfunction. This hybrid device consisting of an ultrathin channel sensitized with absorbing semiconductors while exploiting the characteristics of TFET leads to a new generation of highly sensitive photodetectors.