The Fabrication And Photoelectric Properties Of ZnO Detectors

The technology of ultraviolet detection has been more and more widely applied to production,living and military fields,Ultraviolet detectors with low-cost and excellent-performance have become one of the most popular research directions.As the third-generation wide band gap semiconductor material with direct band gap,ZnO has attracted wide attention in the application of optoelectronic devices due to its excellent characteristics.In order to improve the quality of the ZnO films and enhance its photoelectric performance,so as to prepare better performance ZnO ultraviolet photodetector,the main work in this dissertation carried out as follow:The ZnO films with different annealing process were deposited on the glass substrate by radio frequency magnetron sputtering,it shows that the ZnO film annealed in oxygen atmosphere with 500? has the best film quality and electrical properties.Nb and Sn doped ZnO films were deposited on glass substrates by co-sputtering using direct-current magnetron sputtering at different sputtering powers and consistent radio frequency magnetron sputtering power,the Nb-doped ZnO film decreases the grain size and surface roughness with increasing DC sputtering power,and the optical band gap gradually increases with increasing DC sputtering power,the lowest resistivity and the highest carrier concentration was obtained at 10 W;The Sn-doped ZnO film has the smallest grain size and surface roughness when the DC sputtering power is 15 W,the lowest resistivity and the highest carrier concentration was also obtained at 15 W.The result shows that the annealed and doped films have better film characteristics,which lays the foundation for the performance improvement of the detector.Ultraviolet photodetectors with MSM structure were fabricated on the prepared ZnO film.First,the effects of different electrode material selection on the photodetectors were studied,it is indicated that the Au electrode has better ultraviolet response than the Ag electrode photodetector;Secondly,the effects of different annealing process on the photodetectors were studied,it was found that the ratio of photocurrent and dark current of photodetector was the largest when annealed in oxygen atmosphere at 500?,and the time response was also the fastest,the responsivity under 365 nm ultraviolet light is 1.512 A/W,the detectivity is 2.88×1011 Jones;Finally,the effects of different Nb and Sn doping on the photodetectors were studied respectively,it shows that the ratio of photocurrent and dark current of photodetector is the largest when the Nb-doped DC sputtering power is 10 W,and the time response is more than 6 times higher than undoped device,the responsivity is 5.7 A/W,the detectivity is 1.09×1012 Jones;The ratio of photocurrent and dark current of photodetector reaches 4 orders of magnitude when the Sn-doped DC sputtering power is 15 W,the time response is the fastest,and the responsivity reaches 24.4 A/W,meanwhile,the detectivity reaches 1.62×1013 Jones.The results demonstrated that annealing and doping effectively improve the time response and the responsivity of the ZnO ultraviolet photodetector.Low-cost ZnO ultraviolet photodetectors with good performance were obtained at 15 W Sn-doped DC sputtering power,the work carried out has certain guiding significance for the application of ZnO in the optoelectronic devices field.