Solution-Based Fast Fabrication of a High-Performance Unlimited Area Au Nanostructure/Si Heterojunction Photodetector

High-performing large-area photodetectors are essential for optoelectronic applications. However, the existing photodetectors are limited to small areas, and at larger areas, the response slows down because of increased device capacitance. Capturing photon flux over a large area is particularly important for low-light conditions. Here we report a simple solution method for fabricating a low-cost, large-area photodetector based on light harvesting Au nanostructures grown on a Si substrate leading to a Au silicide (p)–(n) Si active interface. The process is quick, taking only minutes to fabricate a detector of any arbitrary area. This detector exhibits a fast response (～40 μs) and can detect low light intensities (few pW) with high detectivity (～1015 Jones). The device covers a broad spectral range from 300 to 1200 nm. In addition, it shows excellent uniformity throughout the entire 500 mm2 area with <5% variation in response. Notably, the detector operates in self-powered mode with a high on/off ratio (104), thus making it energy efficient. With a commonly available protective coating, excellent environmental stability is shown for the device under the harsh conditions for several days. The photodetector utility is demonstrated as a prototype imaging system, lux and power meter, and also as a tool for security applications