Enhanced performances of Si/CdS heterojunction near-infrared photodetector by the piezo-phototronic effect

Owing to the compatibility with the traditional integrated circuit technology, it is of great significance to enhance the photoresponse performance of Silicon (Si)-based photodetectors (PDs) in the near-infrared (NIR) wavelength. Here, by introducing the piezo-phototronic effect, the photoresponsivity and the specific detectivity of the p-Si/n-CdS heterojunction NIR PD are enhanced by 966 times and two orders of magnitude with a 1064 nm illumination of 0.35 mW cm(-2) power density under -0.50% compressive strain, which is even better than those of commercial Si PDs. The piezo-phototronic effect is a three-way coupling effect of piezoelectricity, semiconductor and optical excitation in piezoelectric semiconductors, such as wurtzite structured CdS. Alternatively, the performance enhancement of the n-Si/n-CdS heterojunction PD by the piezo-phototronic effect is much less than that of the p-n heterojunction PD under the same compressive straining conditions, due to their different energy band structures near the Si/CdS heterojunction. This work provides not only a facile solution-processed fabrication for high-performance Si-based NIR PDs, but also a deep understanding about the piezophototronic effect on the performance enhancement of Si/CdS heterojunction NIR PDs.