| ZnO is a direct band-gap semiconductor (Eg=3.3eV at RT) with a high exciton binding energy of about 60meV. The feasibility of using excitionic lasers of ZnO at RT has been demonstrated. It has been investigated extensively because of its interesting electrical, optical and piezoelectric properties making suitable for many applications such as light emitting diodes, photodetectors, electroluminescence, transparent conductive film, surface acoustic waves device and so on. The renewed interest of ZnO film is fueled since room temoerature lasing was reported by Tang et al.In this thesis, the growth behavior of ZnO films deposited on Si substrate by reactive magnetron sputtering has been studied systematically. The results are summarized as follow:1. Using on-line measurement of plasma emission spectra plasma, components in the plasma was studied with the variation of O2 flow and the deposition temperature. The results show O2 flow important in the determination of sputtering yield of Zn target. When the flow ratio of O2 to Ar+O2 was larger than 0.75%, sputtering yield of Zn target decreased linearly with increasing O2 flow. When the flow ratio of O2 to AM-O2 was in 10%50%, the concentration of oxygen in the plasma varied slowly, being helpful for the control of film growth. The intensity of emission spectrum of atomic Zn at 481.3 run (IZn) varied with increasing deposition temperature (T). When T < 250℃, IZn was approximately a constant. When 250℃ < T < 550℃, IZn increased linearly with increasing deposition temperature. When T> 550℃, IZn increased sharply with increasing deposition temperature.2. The nucleation and growth behavior have been studied for ZnO films. It is found that ZnO film has three nucleation stages. In the initial nucleation stage, the intrinsic defects on Si substrates may be responsible for the surface roughening and the density of surface defects determines the nucleation density of ZnO films. In the low-rate nucleation stage, the deposition rate plays a role of controlling the morphological evolution and the lattice mismatch stress may be released in this stage. The second nucleation of ZnO films may result from the bombardment of energetic ions or atoms on the surface of Si substrates. In the stage of steady growth, ZnO films have a roughness value much lower than the ones in nucleation stages and grow in the form of columnar grains.3. We verify the above model about bombardment effect of energetic ions or atoms on the surface of Si substrates by applied substrate bias. And the nucleation and growth behavior have been studied for ZnO films with -100V bias. It is found that ZnO film has three... |
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