氧化钒薄膜的制备及其太赫兹波段相变性能的研究

发布时间：2018-06-19 12:01

  本文选题：二氧化钒 + 太赫兹调制　； 参考：《电子科技大学》2017年硕士论文

【摘要】：二氧化钒(VO_2)薄膜在太赫兹波段具有良好的热致半导体-金属相变(MIT)性能,在光学调制、开关、存储材料等领域有巨大的应用前景。较低的温度下,VO_2薄膜呈绝缘相,对THz波基本无吸收和色散作用,太赫兹透过率较高。但是随着温度升高超过相变温度后,VO_2薄膜呈金属相,薄膜的太赫兹透过率急剧的减小。我们可以通过热、光、电等外部激励信号控制氧化钒薄膜的相变,使太赫兹波处于透过和不透过的两种不同状态,实现对太赫兹波的调制。VO_2薄膜在THz波段的相变特性,为研究和制备超高速、高调制深度并能在室温附近工作的THz调制器件,填补THz波段缺乏调控材料和器件的缺陷,促进THz波段器件的实际应用具有重要的科学意义和应用价值。为了实现氧化钒薄膜在太赫兹调制器件上的应用,要求氧化钒薄膜具有好的稳定性和可靠性、高的响应率和效率,VO_2应满足四个方面的性能要求:(1)半导体态具有较高的太赫兹透过率;(2)较大的太赫兹调制深度;(3)较小的回线宽度;(4)较低的相变温度。本论文主要围绕制备良好太赫兹调制性能的氧化钒薄膜展开,立足现阶段缺乏高调制幅度的氧化钒薄膜为基点,开展了以下两部分工作:(1)在高阻Si(100)衬底上,利用直流反应磁控溅射法制备相变氧化钒薄膜,探究工艺参数(反应氧流量和溅射电流)对氧化钒MIT性能的影响。在探究工艺参数的实验中,发现靶表面状态的不同也影响着氧化钒的性能,尤其是太赫兹波段的调制深度。进而探究靶表面状态对氧化钒薄膜太赫兹调制深度的影响,在平整靶表面状态下制备了在4.8~6THz波段室温太赫兹透过率约为87%,高温太赫兹透过率约为6%,平均调制深度为93%的氧化钒薄膜。(2)在平整靶表面状态下制备的氧化钒薄膜,虽然在4.8~6THz波段具有高调制深度,但是该薄膜回线宽度较宽(12.4℃),相变温度较高(67.5℃),不能完全满足氧化钒薄膜应用到太赫兹器件的四个性能要求,所以采用贴片法掺杂(Mo和W)来降低薄膜的回线宽度和相变温度。在保持优良太赫兹调制深度(4.8~6THz,83%)的同时,通过掺W(1.5at.%)制备出回线宽度较小(7.7℃),相变温度低(49.1℃)的氧化钒薄膜。
[Abstract]:Vanadium oxide VO _ 2) thin films have good thermo-induced semiconductor-metal phase transition (mitt) properties in terahertz band, and have great application prospects in optical modulation, switching, storage materials and so on. VO _ 2 thin films are insulated at low temperature and have no absorption and dispersion effect on THz wave. The terahertz transmittance is high. However, the THz transmittance of VO _ 2 thin films decreases dramatically when the temperature exceeds the phase transition temperature. The phase transition of vanadium oxide thin films can be controlled by external excitation signals, such as heat, light and electricity, so that the terahertz wave is in two different states of transmission and non-transmission. The modulation of terahertz wave and the phase transition of VO2 thin film in THz band can be realized. In order to study and fabricate ultra-high speed, high modulation depth THz modulation devices which can work near room temperature, it is of great scientific significance and application value to fill the defects of THz band lacking of control materials and devices, and to promote the practical application of THz band devices. In order to realize the application of vanadium oxide thin film in terahertz modulation device, the vanadium oxide film is required to have good stability and reliability. The high response rate and efficiency should meet the requirements of four aspects: 1) the semiconductor state has higher terahertz transmittance and 2) the larger terahertz modulation depth is 3) the smaller loop width and the lower phase transition temperature. This thesis focuses on the preparation of vanadium oxide thin films with good terahertz modulation performance. Based on the lack of high modulation amplitude vanadium oxide thin films at present, the following two parts of work are carried out: 1) on high resistivity Si Si 100) substrates. Phase change vanadium oxide thin films were prepared by DC reactive magnetron sputtering. The effects of process parameters (reactive oxygen flow rate and sputtering current) on the properties of vanadium oxide MIT were investigated. It is found that the different surface states of the target also affect the performance of vanadium oxide, especially the modulation depth of terahertz band. Then the effect of the target surface state on the terahertz modulation depth of vanadium oxide thin films was investigated. Vanadium oxide thin films were prepared under the condition of leveling target surface at 4.8THz room temperature terahertz transmittance of about 87, high temperature terahertz transmittance about 6, average modulation depth of 93% vanadium oxide thin films under flat target surface condition. Although it has a high modulation depth in the 4.8 THz band, the loop width of the thin film is wider than 12.4 鈩，

本文编号：2039814