Preparation And Field Emission Characteristics Of Zinc Oxide Films

Zinc oxide (ZnO) film is a kind of important wide-bandgapⅡ-Ⅵgroup semiconductor film materials with more excellent optical, electronic, magnetic and sensitive properties than block materials, which can be used as field emitter, ultraviolet nanolasers, photodetectors, solar cells, catalysis, and chemical sensors. Therefore, the studies of preparation, properties, growth mechanism and applications are important significance both in basic science and practical application. The main contents of this thesis are shown as the following:1. Using RF magnetron sputtering method, zinc oxide films were prepared on different substrates (e.g., Si, ITO glass, n-Si) with different sputtering parameters under extreme high base vacuum conditions.2. The surface morphology of ZnO thin films was investigated by means of scanning electron microscope (SEM). The films exhibited homogeneous round protuberance, indicating the good crystallization. In order to identify the crystal structures of the synthesized samples and analysis the experimental data, we have calculated the face interval and miller indices for three different ZnO phases. X-ray diffraction (XRD) and Raman spectrum combining the theoretical simulation were employed to characterize the crystalline characteristics and chemical bonding of the synthesized zinc oxide films. The strong (002) peaks of the synthesized samples showed the low energy origin of the c-axis oriented.3. The field emission characteristics of the synthesized ZnO film samples have been measured under ultrahigh vacuum conditions (10-7 Pa). The base pressure: 2.2×10-4Pa, sputtering power:100 W, sputtering time:20 min, substrate:Si, Ar to O2 ratio (3:1,9:1and12:1), sputtering pressure (0.5,1.0,1.9,2.1and 2.5 Pa). I-V and F-N curves have been obtained to analyze the field emission properties of zinc oxide films. The field emission characteristics of the ZnO film deposited at the Ar to O2 ratio of 3:1 and other constant parameters were better than others. The measured turn-on electric field was 7.5 V/μm and the highest emission current density reached 253.3μA/cm2 at the applied field of 55 V/μm. The good field emission properties of the ZnO film fabricated at the sputtering pressure of 2.5 Pa and other constant parameters were obtained. The turn-on electric field was 16 V/μm and the highest current density was 156.5μA/cm2 at the electric field of 53 V/μm.