物理气相传输法制备层状MoS_2薄膜
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摘要
以化学气相沉积(CVD)方法在蓝宝石衬底上沉积一层较厚的MoS_2膜作为前驱体,使用物理气相传输(PVT)方法制备了层状MoS_2薄膜。用光学显微镜、扫描电子显微镜、喇曼光谱和光致发光光谱对制备的层状MoS_2膜表面形貌、层数、光学特性进行了研究。分析了源和衬底距离对MoS_2薄膜沉积的影响,发现距离较近有利于成核概率增大,形成连续膜,但是易引入不稳定因素导致立体生长的MoS_2纳米片,同时观察到出现树枝状生长,这是由于前驱体质量过剩引起的部分晶面生长速率过高导致的。喇曼光谱测试表明,薄膜大部分为单层膜和双层膜,有少量的多层膜,膜的光致发光光谱强度与层数有关,单层膜光致发光光谱强度最强。
A thicker MoS_2 film deposited on a sapphire substrate by the chemical vapor deposition(CVD) method was used as a precursor, then the layered MoS_2 films were prepared by the physical vapor transport(PVT) method. The surface morphology, layer number and optical properties of the prepared layered MoS_2 films were investigated by the optical microscope, scanning electron microscope, Raman spectrum and photoluminescence spectrum. The influence of the distance between the source and substrate on the deposition of the MoS_2 film was analyzed. It is found that a closer distance is beneficial to the increase of nucleation probability and the formation of continuous film, but it is easy to introduce unstable factors to lead to the stereo growth of MoS_2 nanosheets. And the dendritic growth is observed at the same time, which is due to the excessive growth rate of the partial crystal plane caused by the excess mass of the precursor. The Raman spectra show that most of the films are monolayer and bilayer films, with a small number of multilayer films. The photoluminescence spectrum intensity is related to the number of layers, and the photoluminescence spectrum of the monolayer film has the highest intensity.
A thicker MoS_2 film deposited on a sapphire substrate by the chemical vapor deposition(CVD) method was used as a precursor, then the layered MoS_2 films were prepared by the physical vapor transport(PVT) method. The surface morphology, layer number and optical properties of the prepared layered MoS_2 films were investigated by the optical microscope, scanning electron microscope, Raman spectrum and photoluminescence spectrum. The influence of the distance between the source and substrate on the deposition of the MoS_2 film was analyzed. It is found that a closer distance is beneficial to the increase of nucleation probability and the formation of continuous film, but it is easy to introduce unstable factors to lead to the stereo growth of MoS_2 nanosheets. And the dendritic growth is observed at the same time, which is due to the excessive growth rate of the partial crystal plane caused by the excess mass of the precursor. The Raman spectra show that most of the films are monolayer and bilayer films, with a small number of multilayer films. The photoluminescence spectrum intensity is related to the number of layers, and the photoluminescence spectrum of the monolayer film has the highest intensity.
引文
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[3] SPLENDIANI A,SUN L,ZHANG Y B,et al.Emerging photoluminescence in monolayer MoS2 [J].Nano Letters,2010,10(4):1271-1275.
[4] MAK K F,LEE C G,HONE J,et al.Atomically thin MoS2 a new direct-gap semiconductor [J].Physical Review Letters,2010,105(13):136805-1-136805-4.
[5] ZHU W N,YOGEESH M N,YANG S X,et al.Flexible black phosphorus ambipolar transistors,circuits and AM demodulator [J].Nano Letters,2015,15(3):1883-1890.
[6] JARIWALA D,SANGWAN V K,LAUHON L J,et al.Emerging device applications for semiconducting two-dimensional transition metal dichalcogenides [J].ACS Nano,2014,8(2):1102-1120.
[7] LOPEZ-SANCHEZ O,LEMBKE D,KAYCI M,et al.Ultrasensitive photodetectors based on monolayer MoS2 [J].Nature Nanotechnology,2013,8(7):497-501.
[8] LOPEZ-SANCHEZ O,LLADO E A,KOMAN V,et al.Light generation and harvesting in a van der Waals heterostructure [J].ACS Nano,2014,8(3):3042-3048.
[9] YIN Z Y,LI H,LI H,et al.Single-layer MoS2 phototransistors[J].ACS Nano,2012,6(1):74-80.
[10] MENSAH S L,KAYASTHA V K,IVANOV I N,et al.Formation of single crystalline ZnO nanotubes without catalysts and templates [J].Applied Physics Letters,2007,90(11):113108-1-113108-3.
[11] WANG S S,RONG Y M,FAN Y ,et al.Shape evolution of monolayer MoS2 crystals grown by chemical vapor deposition [J].Chemistry of Materials,2014,26(22):6371-6379.
[12] LEE C G,YAN H G,BRUS L E,et al.Anomalous lattice vibrations of single- and few-layer MoS2 [J].ACS Nano,2010,4(5):2695-2700.
[13] LI H,ZHANG Q,YAP C C R,et al.From bulk to monolayer MoS2:evolution of Raman scattering [J].Advanced Functional Materials,2012,22(7):1385-1390.
[14] SPLENDIANI A,SUN L,ZHANG Y B,et al.Emerging photoluminescence in monolayer MoS2 [J].Nano Letters,2010,10(4):1271-1275.
[15] ZHANG Y,ZHANG Y F,JI Q Q,et al.Controlled growth of high-quality monolayer WS2 layers on sapphire and imaging its grain boundary[J].ACS Nano,2013,7(10):8963-8971.