Advancing Mid-Infrared Detection in Silicon-Based Schottky Photodetectors via Metal Film Morphology and Hot Carrier Effect

This study explores methods to enhance the responsivity of silver/silicon Schottky diode-based photodetectors in the mid-infrared wavelength range. Traditional infrared photodetectors primarily use compound semiconductors, but their scarcity and high cost limit application areas. This research employs silicon as the main material to reduce processing costs and improve integration with integrated circuits (ICs). By forming a Schottky contact between the metal and silicon, this study utilizes the internal photoemission absorbance mechanism to effectively extend the detection range to infrared light with energy lower than the semiconductor bandgap. Additionally, by controlling the morphology of the metal thin film to induce stronger local surface plasmon resonance, the absorbance and responsivity of light are significantly enhanced. The results show that under a 3460-nm infrared light source, the responsivity increased from 0.4154 to $3.8615~\mu $ A/W, nearly a tenfold improvement. Furthermore, through the study of hot carrier generation and diffusion, the responsivity of the device in the mid-infrared wavelength range was further enhanced, reaching $11.0964~\mu $ A/W. Moreover, the device could measure signals at wavelengths up to 6000 nm, surpassing the cutoff wavelength limitation. This demonstrates that the methods used in this study can effectively improve the performance of silicon-based Schottky detectors.