In this article, we present a time-dependent model that enables us to describe the dynamic behavior of pulsed DC reactive sputtering and predict the film compositions of VOx prepared by this process. In this modeling, the average current J is replaced by a new parameter of Jeff. Meanwhile, the four species states of V, V2O3, VO2, and V2O5 in the vanadium oxide films are taken into consideration. Based on this work, the influences of the oxygen gas supply and the pulsed power parameters including the duty cycle and frequency on film compositions are discussed. The model suggests that the time to reach process equilibrium may vary substantially depending on these parameters. It is also indicated that the compositions of VOx films are quite sensitive to both the reactive gas supply and the duty cycle when the power supply works in pulse mode. The ＇steady-state＇ balance values obtained by these simulations show excellent agreement with the experimental data, which indicates that the experimentally obtained dynamic behavior of the film composition can be explained by this time-dependent modeling for pulsed DC reactive sputtering process. Moreover, the computer simulation results indicate that the curves will essentially yield oscillations around the average value of the film compositions with lower pulse frequency.
In this paper, an improved sol-gel method was suggested to obtain high-concentration LiTaO3 precursor solution for simplified experimental conditions and thicker films, by mixing lithium acetate and tantalum ethoxide in a 1, 2-Propylene glycol solution. Compared to traditional methods, the process was done without weak acidic solution and absolute dry experimental condition. Results of a comparative study of LiTaO3 thin films derived by the improved sol-gel process and a traditional process using 2-methoxy ethanol as solvent were presented. Nano-crystalline LiTaO3 films with rhombohedral structures were formed in both methods after annealing at 650℃ for 5 min. The thickness of each LiTaO3 layer coated onto the substrate increased from 25 nm to 110 nm when 2-methoxy ethanol was replaced by 1, 2-Propylene glycol. LiTaO3 films with a stronger preferential orientation were obtained in 1, 2-Propylene glycol due to its higher boiling point and slower volatilization rate. On the other hand, the diffraction peak intensity of LiTaO3 thin films prepared using 1, 2-Propylene glycol was weaker than that of the films prepared using 2-methoxy ethanol due to decreased times of annealing.
Jun GOUJun WANGMing YANGZehua HUANGWeizhi LIYadong JIANG
In this paper an original numerical model, based on the standard Berg model, is used to simulate the growth mechanism of Ti-doped VOx deposited with changing oxygen flow during reactive sputtering deposition. Ti-doped VOx thin films are deposited using a V target with Ti inserts. The effects of titanium inserts on the discharge voltage, deposition rate, and the ratio of V/Ti are investigated. By doping titanium in the vanadium target, the average sputtering yield decreases. In this case, the sputter erosion reduces, which is accompanied by a reduction in the deposition rate. The ratio between V content and Ti content in the film is measured using energy-dispersive x-ray spectroscopy （EDX）. A decrease in the vanadium concentration with the increasing of the oxygen flow rate is detected using EDX. Results show a reasonable agreement between numerical and experimental data.
采用Rt-silica Bond Plot毛细管色谱柱(硅胶键合极性基团固定相)的GC-FPD色谱系统,检测了环境中的含硫恶臭气体甲硫醇、甲硫醚、乙硫醇、二硫化碳和二甲二硫的混合气体。实验研究了气相色谱柱进样口压力和升温方式对分离效果的影响,在最佳分离条件下对5种气体的混合样进行了重复性测试,并利用自制的Tenax管式富集器分析5种气体的检出限。方法的最佳进样口压力为48.26 k Pa和最佳升温方式为初始温度160℃,以30℃/min升至220℃,可以实现混合气体的完全分离,分离时间3.850 min,组分间最小分离度2.525,最佳条件下具有很好的重复性,保留时间和组分分离度的相对标准偏差均小于1%,峰面积相对标准偏差最大为5.0%,5种气体的检出限依次为45,37,21,30和22μg/m3。
