High-performance Si/VO2-nanorod heterojunction photodetector based on photothermoelectric effect for detecting human radiation

As a typical candidate of optoelectronic materials, vanadium dioxide (VO2) has wide applications in photodetectors (PDs), but is still challenging in largely enhancing the photodetecting performance for low-power human radiation. Herein, high-performance Si/VO2 nanorods (NRs) heterojunction PDs based on the photothermoelectric (PTE) effect are presented. The uniform VO2-NRs array films were deposited on Si by using magnetron sputtering technique, and a Si/VO2 heterojunctions were fabricated. The device exhibits a four-stage photoresponse and broadband photoresponse from ultraviolet to long-wavelength infrared. Benefited from the unique nanorods structure and the strong PTE effect, the fabricated device exhibits a large enhancement of the photodetecting performance, showing an ultrahigh photodetectivity of 1.6 x 10(13) Jones and ultrafast response rates with a rising-edge time of similar to 65.0 mu s, three orders of magnitude higher than other VO2-based devices. Furthermore, the device exhibits unique abilities to detect human radiation even when the human fingers are far away from the device surface up to 10.0 cm. Additionally, the fabricated Si/VO2 devices can also be applied as breath sensors to distinguish different breathing patterns. These results supply an effective route to design high-performance photodetectors toward detecting human thermal radiation and respiration.