Novel solar-blind ultraviolet photodetector based on inserting sputtered ITO ultrathin film for integrated silicon photonics platform

摘要

In this paper, a new UV-photodetector (UV PD) design based on non-hydrogenated amorphous-silicon (a-Si) was fabricated using RF magnetron sputtering technique. The proposed structure consists on sputtering an ITO thin-film acting as a passivation layer on the a-Si layer to form a heterostructure design compatible with silicon photonics technology. X-Ray Diffraction (XRD) and UV-Vis spectra were carried out to assess the device structural and optical properties. Measurements emphasized the amorphous state of the sputtered Si thin-film. Interestingly, it was found that the elaborated device shows an exciting UV absorption capability (over than 95%) with drastically reduced visible photoresponse. The elaborated ITO/a-Si UV PD exhibits an ultra-low dark current less than 1 pA, a good responsivity of 0.13 A/W and a high I_(on)/I_(off) ratio of 2.5 × 10~4. Besides, the device demonstrates a high UV-to-Vis ratio exceeding 2.3 × 10~3, thus confirming its visible blindness property. These enhancements are attributed to the role of ITO/a-Si heterostructure in promoting near-perfect UV absorption. In addition, this structure generates an electric field acting as effective driving force of the photo-induced e/h pairs, which leads to enhance the device generation/collection efficiency. Therefore, the use of ITO/a-Si design opens up new pathways for designing novel solar-blind UV PDs potentially appropriate for integrated silicon photonics technology.