The Influence of Surface Treatment on the Performance of Photoconductive Detectors Based on Silicon Wafer

Owing to its narrow bandgap and mature preparation process, silicon wafers were widely used to prepare broadband photodetection devices. To address the issue of weak light absorption in the ultraviolet (UV) and infrared regions, surface treatments including sanding by sandpaper and etching by hot alkaline solution were carried out in this article. Numerous defects and microstructures were formed on the surface of the silicon wafer after sanding treatment. Compared with the sanding treatment, hot alkaline solution etching can introduce a few defects and small microstructures, leading to significant enhancement of photocurrent in the entire UV-vis-near-infrared (NIR) region. The responsivity of this silicon-based photoconductive detector has been increased by one order of magnitude when the silicon wafer was etched in NaOH solution at $95~^{\circ }$ C. The main reason for this enhancement is the increase of carrier transport efficiency, resulting from the generation of defects on the surface. The obtained results provide new insight and route for the further development of silicon-based optoelectronic devices.