Research Of Preparation And Properties Of ZnO Photodetector Based On Nanoimprinting Technology

As an important II-IV semiconductor oxide, zinc oxide (ZnO) has a wide band gap of 3.37eV at room temperature, corresponding to the ultraviolet photon energy. With these properties ZnO is suitable for fabricating high-performance ultraviolet photodetector. For flat ZnO thin film photodetector, the light absorption performance of ZnO is limited. Many researchers fabricated one-dimensional and two-dimensional nanostructure to increase the specific surface area of ZnO to improve the light absorption performance of ZnO thin film. Because the preparation technology of ZnO one-dimensional and two-dimensional nanostructure is complicated, it is not suitable for preparation large area ZnO photodetector. In our work, direct thermal nanoimprinting method was employed to prepare three-dimensional ZnO nanostructure. In addition, when ZnO thin film doped with noble metal nano-particle, the photo-response region of ZnO photodetector has been extended from ultraviolet region to visible region due to the surface plasma effect.Firstly, ZnO precursor sol has been prepared by sol-gel method. Then, ZnO thin film with three-dimensional nanostructure has been fabricated by direct thermal nanoimprinting method. The photo-current of ZnO thin film with three-dimensional nanostructure has improved 15 times compared with flat ZnO thin film photodetector.Then, Au nano-particles were prepared by sol-gel method. The Au nano-particles can extend the photo-response region of ZnO thin film photodetecter from 400nm to 530nm, due to surface plasma of Au nano-particles. Furthermore, we combined the nanoimprinting method and surface plasma effect of Au nano-particles to fabricated high performance ZnO-Au thin film photodetector. The photo-current of patterned ZnO-Au thin film is 26 times compared with the photo-current of flat ZnO thin film photodetector.Finally, the physical dimension is a crucial parameter for nanometer materials. Thus, we fabricated photodetector with different depth-to-width ratio to explore the optimum depth-to-width ratio. Furthermore, Au nano-particles were doped into ZnO photodetector. The photo-current of ZnO-Au thin film with depth-to-width ratio 866nm/40nm is 208 times compared with flat ZnO thin film photodetector.