Performance Evaluation and Reliability Insights for Silicon Nanowire Reconfigurable Phototransistors

This work presents, for the first time, a rigorous investigation of the optical sensing performance and design of silicon nanowire (Si-NW) reconfigurable phototransistors (RPTs) over a broadband wavelength range spanning the ultraviolet (UV), visible, and near-infrared (NIR) regions. To study the design of these RPT devices, a well-calibrated simulation framework is developed under both dark and illuminated conditions to evaluate and compare the electronic, transfer, transient, and optical characteristics for p-type and n-type operation. The baseline device exhibits a peak responsivity of 180 mA/W and a photosensitivity of 5 × 10⁴ within the UV and visible spectral ranges. The reliability of the optical sensing performance is further evaluated by modifying the gate overlap position of the control and program gates on the nanowire channel while keeping the original physical process parameters unchanged. The influence of control and program gate positions is analyzed through energy band diagrams, carrier density profiles, responsivity, and dark current characteristics. Optimal gate placements are identified to enhance photo-absorption without adversely affecting the dark-state transfer characteristics or the physical baseline device dimensions. With optimized control and program gate positions, a peak responsivity of 315 mA/W is achieved, representing an enhancement of ~1.8× while maintaining reliable electrostatic behavior of the RPT devices. This study establishes a promising foundation for integrating Si-NW RPT into advanced CMOS-compatible on-chip photonic platforms targeting UV, visible, and NIR wavelength detection.