基于石墨烯的宽带太赫兹波调控技术研究

发布时间：2018-12-31 18:45

【摘要】：太赫兹波在无线通信、反恐安保、医药检测、高分辨无损成像等领域具有巨大的应用潜力。构建实用化的太赫兹应用系统,在源和检测器件之外,还需要研制高性能的太赫兹传输调控器件。近年来,石墨烯因其独特的能带结构和电学输运性能受到广泛关注,石墨烯在太赫兹功能器件领域也展现出巨大的潜在应用价值。本论文以此为研究背景,分别采用光学调控和电学调控两种方式实现并制备了基于石墨烯的THz波调制器,并对其不同情况下的THz波调制性能做了深入研究。首先,本论文研究了化学气相沉积法(CVD)制备的大面积石墨烯的转移方法,并对转移石墨烯的工艺流程和工艺参数进行了优化。通过对石墨烯转移工艺的优化,有效解决了在传统转移工艺中石墨烯表面容易残留金属杂质颗粒和光刻胶残留的问题。然后,利用以高阻硅片为衬底的石墨烯薄膜,在光激发下产生大量光激发载流子,使得THz波透射率下降的效应,研究并制备了硅基石墨烯THz波光控调制器。然而,石墨烯表面因易受到表面杂质、水汽吸附和荷电杂质散射等影响,导致石墨烯的迁移率,跨导等电学性能的大幅下降。本文通过旋涂不同厚度的3-氨基丙基三乙氧基硅烷(3-AT)和二甲基甲砜(DMSO)对石墨烯薄膜进行表面改性,改善石墨烯输运性能,进而增强对THz波的调制效果。最后,制备基于石墨烯场效应晶体管的THz波调制器。在本项工作中,我们提出一种石墨烯晶体管(GFET)太赫兹波调制器件。该调制器采用Al2O3来代替传统的Si O2栅介质层。氧化铝相较于二氧化硅具有较高的介电常数,可以有效地减少石墨烯的库仑散射和腔体效应,从而获得较大的石墨烯晶体管(GFET)跨导。研究表明,较大的跨导可以提高太赫兹波调制器的调制深度和调制速度。我们研制出在0.4THz至1.5THz范围内可用的宽带太赫兹波调制器,调制深度达到22%,调制速率为170 KHz,为研制更好性能的太赫兹调制器提供了新的思路。
[Abstract]:Terahertz wave has great potential in wireless communication, anti-terrorism security, medical testing, high-resolution nondestructive imaging and so on. To construct a practical terahertz application system, it is necessary to develop high performance terahertz transmission and control devices in addition to the source and detection devices. In recent years, graphene has attracted much attention because of its unique band structure and electrical transport properties. Graphene has shown great potential application value in terahertz functional devices. In this thesis, the THz wave modulator based on graphene is realized and fabricated by optical and electrical modulation, and the modulation performance of THz wave in different conditions is studied in detail. Firstly, the transfer method of large area graphene prepared by chemical vapor deposition (CVD) was studied in this paper, and the technological process and process parameters of transfer graphene were optimized. Through the optimization of graphene transfer process, the problem of metal impurity particles and photoresist residues on the surface of graphene was solved effectively in the traditional transfer process. Then, using graphene thin films on high resistance silicon substrates, a large number of photoexcited carriers are produced under photoexcitation, which results in the decrease of THz wave transmittance. A silicon-based graphene THz wave-controlled modulator is studied and fabricated. However, the surface of graphene is easily affected by surface impurities, water vapor adsorption and charged impurity scattering, which results in a significant decrease in the mobility, transconductance and other electrical properties of graphene. In this paper, the surface modification of graphene thin films with different thickness of 3-aminopropyltriethoxy silane (3-AT) and dimethyl sulfoxide (DMSO) was carried out to improve the transport properties of graphene and to enhance the modulation effect of THz waves. Finally, the THz wave modulator based on graphene field effect transistor is fabricated. In this work, we propose a (GFET) terahertz wave modulator for graphene transistors. The modulator uses Al2O3 instead of the traditional Si O 2 gate dielectric layer. Compared with silica, alumina has a higher dielectric constant, which can effectively reduce the Coulomb scattering and cavity effect of graphene, and obtain a larger graphene transistor (GFET) transconductance. The results show that the larger transconductance can improve the modulation depth and speed of THz modulator. We have developed a wideband terahertz wave modulator in the range of 0.4THz to 1.5THz. The modulation depth is 22 and the modulation rate is 170 KHz, which provides a new idea for the development of terahertz modulator with better performance.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN761

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