Near-Infrared Phototransistor Using a SiGe-Based Light-Triggered Feedback Field-Effect Transistor with a Metasurface

Abstract

This work presents a near-infrared (NIR) phototransistor, the light-triggered feedback field-effect transistor (LT-FBFET), which offers high current gain, low dark current, low static power dissipation, and compatibility with CMOS technology. A 20 nm SiGe alloy in the light-absorbing layer extends the operational wavelength to 1310 nm, enhancing quantum efficiency while maintaining low power consumption. The LT-FBFET operates via NIR absorption in the gate region, eliminating the need for external gate bias. Finite-difference time-domain (FDTD) and technology computer-aided design (TCAD) simulations demonstrate the optimized device’s performance, achieving a quantum efficiency of 48.9 at a drain bias of 0.51 V and a static power dissipation on the order of 10^–6 W/cm². The fabricated device confirms the LT-FBFET’s optical switching behavior under 1310 nm NIR illumination. A metasurface consisting of a periodic array of LT-FBFETs was constructed to enhance performance, significantly increasing light absorption via Mie resonance. In addition, adjusting the size and periodicity of the LT-FBFETs enabled tuning of the operating wavelength to 1200 nm and achieving polarization selectivity, as validated by TCAD and FDTD simulations.