Trigonal (1T) and hexagonal (2H) mixed phases MoS2 thin films
Trigonal (1T) and hexagonal (2H) mixed phases MoS2 thin films
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DOI：
10.1016/j.apsusc.2018.02.218
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发表时间：
2019-04
影响因子：
6.7
通讯作者：
S. Sarma;S. Ray
中科院分区：
文献类型：
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作者：
S. Sarma;S. Ray
采用浸渍-提拉法，在400 °C-450 °C范围内，用NaHCO 3和硫氰酸铵的甲醇溶液在不同的焙烧温度下制备了厚度<1500 μ m的二硫化钼薄膜，并利用X射线衍射（XRD）、紫外-可见光谱、光致发光（PL）、X射线光电子能谱（XPS）、紫外光电子能谱（UPS）和电流-电压（I-V）关系测量。XRD结果表明，MoS 2薄膜为金属八面体棱柱1 T-和三角棱柱体2 H-相的混合体晶。I-V关系显示在400 °C和450 °C下制备的膜比在425 °C下制备的膜具有更高的电导率。XPS测量也显示了MoS 2薄膜的混合相的形成，如XRD所揭示的。利用425 °C和450 °C下制备的MoS_2薄膜的UPS（He-I）高、低能区谱，估算了薄膜的价带顶（VBM）和功函数。VBM值分别为4.4 eV和4.2 eV，功函数分别为3.5 eV和3.3 eV，它们与MoS 2薄膜的电导率和混合相的形成有关。
Molybdenum di-sulfide thin films of thickness <1500 Å, were prepared by the dip-coating technique at different baking temperatures within the range 400 °C–450 °C using methanolic solution of ammonium molybdate and ammonium thiocyanate and hence studied their different properties using X-ray diffraction (XRD), UV-vis spectroscopy, Photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS) and Current-Voltage (I-V) relationship measurements. XRD result shows that the MoS2films are mixed metallic octahedral prismatic 1T- and trigonal prismatic bulk crystal 2H-phases. The I-V relationships show higher electrical conductivity for the films prepared at 400 °C and 450 °C than the films prepared at 425 °C. XPS measurement also shows the formation of mixed phases of MoS2thin films as revealed by XRD. We have estimated the valence band maximum (VBM) and work functions from higher and lower energy range of UPS (He-I) spectra of MoS2thin films prepared at 425 °C and 450 °C. The VBM are ∼4.4 eV & ∼4.2 eV and their work functions are ∼3.5 eV & ∼3.3 eV respectively that are correlated with conductivity and formation of mixed phases of MoS2thin films.