Performance Investigation of an L-Shaped Tunneling Gate TFET Photodetector for Near-Infrared Detection

This study introduces an innovative photodetector device that integrates an L-shaped top gate with a photosensitive back gate (LTG-PBG-TFET), specifically engineered to detect incident light within the near-infrared (NIR) wavelength range of 750–1050 nm. The LTG-PBG-TFET design leverages the advantages of both the L-shaped top gate and the photosensitive bottom gate to extend the edge tunneling zone at the channel/source (C/S) junction. This structural configuration enhances the photocurrent (Ilight) response, subthreshold swing (SSavg), and turn-ON voltage (Vth) under illumination. Furthermore, the slight elevation near the gate corner minimizes corner effects at the source/channel interface, which in turn improves Ilight/Idark performance as the illumination wavelength (λ) transitions from 1050 to 750 nm. Consequently, notable enhancements in Ilight, SSavg, and the Ilight/Idark ratio were observed, yielding a high spectral sensitivity (Sn) of approximately 54.4 and a signal-to-noise ratio (SNR) of about 82.2 for the proposed LTG-PBG-TFET device. Additionally, incorporating a light exposure window in the back gate region increases the active area for electron-hole pair (EHP) generation, thereby enhancing quantum efficiency (η) and responsivity (R), particularly at longer wavelengths around 1050 nm. Finally, the influence of acceptor–donor trap charges at the semiconductor/oxide interface on the Sn of the device was examined. Results indicate that Sn remains relatively stable as the wavelength (λ) is tuned between 750 and 1050 nm.