The Influence Of Different Doping Fe On ZnO Films' Luminescence Performance And The Study On The Structure Of ZnO Films With A SiO₂ Thin Buffer Layer

With the development of information technology, the material of optoelectronic information is one of the extremely greatest concerns of the material. ZnO is multifunctional semiconductor material. It is a new-type semiconductor with a high exciton binding energy of 60meV. ZnO has been investigated extensively because of its interesting electrical, optical and piezoelectric properties making suitable for many applications such as photodetectors, light emitting diodes, electroluminescence, surface acoustic waves device, transparent conductive film and so on.ZnO films have been grown by various deposition methods and research methods including magnetron sputtering, pulsed laser deposition, metal organic chemical vapor deposition, spray pyrolysis, sol-gel process and X-ray diffraction, atom force micro- scopy, UV-visible spectrophotometry, fluorescence spectrophotometer. Magnetron sputtering method is widely used by the researchers because the equipment is simple, low cost, easy operation, high rate of deposition, the requirement of base temperature is lower and good film adhesion, its ingredients in a certain extent controllable, etc.In this thesis, we researched the effect of different Fe doping, the deposition time of SiO₂ buffer layers on the structure and optical property of ZnO films deposited by magnetron sputtering with RF and co-reactive magnetron sputtering with RF. In this way some experimental data and the theoretical basis are provided for the application of ZnO films. The results are summarized as follows:1. The influence of different Fe doping on the property of ZnO films have been studied on glass substrates. It is found that the FWHM (half high peak width) of ZnO(0 0 2)decreased gradually, the grain size grew up and the lattice constant along c-axis grew up, which indicate that the Fe has into the crystallization of the ZnO films.2. We studied the influence of different Fe doping on the photoluminescence (PL) properties of ZnO films on Si substrates by using fluorescence spectrometer. The photoluminescence characteristics of Fe-ZnO show the blue luminescence peak and green luminescence peak. The blue emission corresponds to the electron transition from the bottom of the conduction band to the acceptor level of zinc vacancy; the green emission corresponds to the electron transition from the oxygen vacancy to zinc vacancy and from the bottom of the conduction band to the local level composed of oxide misplaced defects.3. The transmission spectrum and absorption spectrum of Fe-ZnO show that Fe-ZnO films possess an average transmittance of about 66% in the visible region; the band gap of Fe-ZnO with 2% doping is close to the band gap of ZnO.4. The influence of different deposition time of SiO₂ on the property of ZnO films has been studied on glass substrates. It is found that as the deposition time of SiO₂ layers increases up to 40 min, the FWHM of ZnO films reaches a minimum, the grain size of ZnO films reaches a maximum, and the tensile strain reaches a minimum about 1.8040 Gpa, which indicate that the crystalline quality of ZnO film can be improved greatly due to the introduction of compliant SiO₂ buffer and the optimal deposition time is 40 min for the better growth of ZnO films. Root mean square (RMS) surface roughness values for these films were less than five nanometer, indicating that the films are indeed quite smooth by Atomic force microscopy.5. The influence of different annealing temperature on the property of ZnO/SiO₂ films has been studied on glass substrates. It is found that as the annealing temperature increases up to 500℃, the samples possess three peaks of (100), (002), (101) of ZnO films are located at 31.76°, 34.26°, 36.27°, demonstrating a polycrystalline hexagonal wurtzite structure. Moreover, the intensity of ZnO films decrease dramatically compared with as-deposited ZnO films. Above all, the crystalline quality of ZnO films becomes worse by heat treatment process.6. The transmission spectrum and absorption spectrum of ZnO/SiO₂ show that the average transmission of films in the visible range 300-800 nm was more than 90%. This is the same as the pure ZnO. We believe that it has no influence of the deposition time of SiO₂ buffer layers on the transmission property of ZnO films.