| In the technological advanced society, semiconductor thin film material with its excellent features and special small size effect is gradually becoming the mainstream in this field. At present, more extensive researches are focusing on the zinc-based materials and nitrogen compounds, while Zn3N2 is a special compound belongs to both these two types of materials. Therefore, in recent years more and more people gradually begin to show their interests to Zn3N2 research. Zn3N2 has a high electrical conductivity, high carrier mobility efficiency, low manufacturing cost, and etc. It has large band gap and the width is adjustable. P-type ZnO can be fabricated from the oxidation of intrinsic n-type Zn3N2 thin film. In this way can it help solve the problem of low solid solubility of acceptor impurities which the acceptor doping technique has trapped into previously.RF reactive magnetron sputtering technique was employed to deposit Zn3N2 thin film under varied sputtering powers, N2-Ar gases flow rates, substrate types and temperatures. A variety of detection methods were applied to analyze lattice structure, preferred orientation, grain size, surface morphology, optical and waveguide properties of the films grown under different experimental conditions.Quartz glass, silicon<100> and<111> were selected as three different substrates for Zn3N2 thin film to grow on. After detected by XRD, film sample fabricated on quartz glass substrate had a maximum grain size, the strongest diffraction peak and preferred orientation in the same set of experiments, otherwise the film structure turned to be polycrystalline.Zn3N2 films were prepared on quartz glass at varied sputtering power. XRD analysis showed that when the sputtering power ranged from 30W to 60W, the film structure was single crystalline, only having the (321) preferred orientation. The grain size increased with increasing sputtering power. When sputtering power increased to 90W, the film structure was polycrystalline, with (400) and (600) diffraction peaks appearing. The preferred orientation turned from (321) to (400), grain size continued to increase. When the sputtering power rose to 150W continue, due to the deterioration of the film and substrate adhesion ability, film quality began to decline. The effective refractive index of TE and TM mode for Zn3N2 thin film waveguide were measured by prism coupling method at a wavelength of 633 nm. It was found that the effective refractive index was greater than the refractive index of the substrate, illustrating Zn3N2/SiO2 film waveguide was formed.The crystal quality and grain size of film prepared under varied N2-Ar flow ratio conditions were studied by XRD. More Zn3N2 generated with the N2-Ar flow ratio rose from 2:3 to 3:2. The crystal structure was polycrystalline, and the grain size increased when the N2-A1 flow ratio equaled to 3:2. When N2-Ar flow ratio reached up to 4:1, the film is a single crystal structure with only (321) diffraction peak, but the peak intensity of diffraction and grain size had continued to increase. The UV-visible spectrophotometer analysis indicated that with N2-Ar flows ratio increases, the transmittance of the film decreased, indicating that the film thickness increased, and the density was improved meanwhile. The average optical transmittance of Zn3N2 film was high to visible and even ultraviolet light, indicating a large band gap. XRD results showed when the substrate heated to 200"C, grain size was smaller than that of room temperature. The results showed that high substrate temperature was not conducive to the growth Zn3N2 film. The surface appearances of the Zn3N2 fabricated on quartz glass substrate was investigated by SEM and AFM. SEM test results showed that the film grain sizes were uniform, arranged neatly and compactly, having clear hexagonal columnar grains. AFM results indicated that the arithmetic average roughness (Rq) and the average surface roughness (Ra) were 3.45nm and 2.46nm, illustrating that the overall arrangement of Zn3N2 particles were uniform, dense and the surface was smooth. Prism coupling analysis showed that Zn3N2/SiO2 film waveguide structure had been obtained both on the room temperature and heated substrates, merely that the refractive index of the film on the heated substrate was smaller than that on the substrate at room temperature. |
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