Improved Performance of Near-Infrared $\bf{S}{{\bf{i}}_{1 - x}}\bf{S}{{\bf{n}}_x}/\text{Si}$ Metal-Oxide- Semiconductor Field-Effect Phototransistors by Utilizing the Grating-Gate

Abstract

This letter presents that novel grating-gate (GG) $\mathrm{S}{{\mathrm{i}}_{1 - x}}\mathrm{S}{{\mathrm{n}}_x}$ p-channel metal-oxide-semiconductor field-effect phototransistors (MOSFEPTs) grown on the Si platform are explicitly designed for near-infrared (NIR) photodetection applications. The proposed device can be fabricated using 0.8-μm complementary-metal-oxide semiconductor (CMOS) technology and addresses the challenge of integrating a detector with CMOS processing circuits. The proposed structure utilizes the GG to enhance the transmission and absorption of incident light into the channel, leveraging the principles of Fabry–Perot and surface plasmon resonance. Furthermore, the GG plays a crucial role in minimizing the drain current under dark by effectively reducing the gate leakage current. The result demonstrates that the MOSFEPT featuring a GG achieves a drain current (I_DS = ∼0.73 μA at V_GS = −3 V and V_DS = −1.5 V) that is two orders of magnitude lower in the dark than the conventional-gate MOSFEPT (I_DS = ∼68.8 μA at V_GS = −3 V and V_DS = −1.5 V). Thus, the MOSFEPT with a GG demonstrates a remarkable detectivity value of $2.15 \times {{10}^{10}}$ Jones and a low noise-equivalent power value of $1.46 \times {{10}^{ - 13}}$ WHz^−0.5 at λ = 850 nm. Furthermore, the MOSFEPT featuring a GG achieves exceptionally high responsivity and external quantum efficiency of 5.06 A/W and 674%, respectively, at λ = 850 nm with ${{V}_{\text{DS}}}$ V_DS = −1.5 V and ${{V}_{\text{GS}}}$ V_GS = −3 V, exceeding previously reported values and highlighting its potential for advanced NIR detection applications.