Study On The Fabrication Of Nitrogen And Phosphorus Doped ZnO Films By Using Two Step Method

As a kind of new multifunctional semiconductor material, ZnO has been tremendously popular to the science researchers in many fields and considerably studied in recent years. The study on its preparation method and property is favorable to the better application in panel displays, optoelectronic devices, photocatalytic devices and sensors. In this parper, we mainly adopted the two-step method (i.e combination of magnetron sputtering and hydrothermal method) to achieve nitrogen and phosphorus-doped ZnO films. Furthermore, the samples fabricated under different conditions were conducted chacterization and analysis of of surface morphology, crystalline structure and optical property. The main conclusions were drawn as followed:(1) ZnO films with<002> preferred orientation were prepared on glass slides by using direct-current magnetron sputtering. The<002> preferred orientation is strengthened and then weakened with the increasing in sputtering time. The<002> preferred orientation of the films is best at the sputtering time of30mins. The average transmissivity of samples is above80%in the visible region. The transmission region gradually narrows down with the increasing in sputtering time. And the average transmissivity reaches the minimum at the sputtering of30mins.(2) The<002> oriented ZnO film magnetron sputtered for30mins was nitrogen doped by using hydrothermal method. Hydrothermal doping destroys the original uniformity and compactness of the films, making the surface paricle size uneven and the emergence of holes. The doping of nitrogen into the crystal makes the shift of the (002) diffraction peak obvious, and the growth of the<002> preferred orientation is gradually reduced with the doping concentration increasing. Hydrothermal reaction initially weakens the<002> preferred oriention and then enhances the<002> preferred oriention.(3) Hydrothermal reaction includes the nitrogen doping and the etching precesses. The initially predominated nitrogen doping is harmful for the<002> preferred orientation, and the latter predominate etching reaction is just the opposite.(4) With the increase in the doping concentration, the absorption edges and the forbidden-band luminescence center of the free excitons of the ZnO:N films first red shift and then blue shift,, indicating that hydrothermal reaction first introduces more defects and then results into the increase in free carrier concentration in the films. Near488nm gradually appears a green-blue luminescence wave package, resulting from the substitution for oxygen by nitrogen.(5) The<002> oriented ZnO films magnetron sputtered for15mins were phosphorus doped by using hydrothermal method. Hydrothermal reaction includes the growth of ZnO and phosphorus doping. The surface morphology of the films mainly depends on the concentration of ammonium dihydrogen phosphate and the hydrothermal reaction.(6) With the increase in the concentration of ammonium dihydrogen phosphate and the hydrothermal reaction time, the<002> preferred orientation of ZnO tends to be weakened and is not observed at high concentration of ammonium dihydrogen phosphate; with the increase in concentration of ammonium dihydrogen phosphate and the hydrothermal reaction time, a shift of the asymmetric luminesence peak near393nm occurs and a visible light emission wave envelope exists near550nm.As the concentration of ammonium dihydrogen phosphate increases, the band edge of the transmission and absorption obviously blue shifts until0.005M, In order to obtain the fine ZnO:P films, the proper concentration of ammonium dihydrogen phosphate is0.002M and the optimal hydrothermal reaction time is18h.