Polymorph-Selective Deposition of High Purity SnS Thin Films from a Single Source Precursor
Polymorph-Selective Deposition of High Purity SnS Thin Films from a Single Source Precursor
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DOI：
10.1021/acs.chemmater.5b03220
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发表时间：
2015-11-24
影响因子：
8.6
通讯作者：
Peter, Laurence M.
中科院分区：
文献类型：
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作者：
Ahmet, Ibbi Y.;Hill, Michael S.;Peter, Laurence M.
金属硫族化合物薄膜具有广泛的应用前景。硫化锡（II）是一种这样的材料，其提出了对高质量SnS的需求的重大挑战，不含氧化物材料（例如，SnO2）和更高级的锡硫化物（例如，Sn2S3和SnS2）。当靶材料表现出许多具有不同光电性质的多晶型时，该问题进一步复杂化。与严重依赖于具有挥发性、稳定性和反应性的前体的常规化学气相沉积（CVD）和原子层沉积（ALD）不同，气溶胶辅助CVD（AA-CVD）的使用消除了对挥发性前体的需要。我们在这里报告，为第一次，新的和结构特征的单一来源前体（1），（二甲氨基）（N-苯基-N '，N'-二甲基硫代硫酸盐）锡（II）二聚体，和它的应用中的沉积，通过AA-CVD，相纯薄膜的SnS。还报道了从前体1氧化控制形成SnS的机制。值得注意的是，沉积过程的热控制允许正交-SnS（α-SnS）或掺锌-SnS（ZB-SnS）多晶型物的前所未有的选择性和排他性形成。α-SnS或ZB-SnS薄膜已分别在375和300摄氏度的优化沉积温度下沉积到Mo、氟掺杂氧化锡（FTO）、Si和玻璃衬底上。通过X射线衍射、扫描电子显微镜、原子力显微镜、拉曼光谱、能量色散X射线光谱和X射线光电子能谱分析表征了密集堆积的多晶薄膜。这些数据证实了所形成的SnS的相纯度。光学分析的α-SnS和ZB-SnS膜显示出明显不同的光学性质，直接带隙分别为1.34和1.78 eV。此外，进行光电化学和外量子效率（EQE）测量，以评估沉积样品的光电性能。我们还首次报道了ZB-SnS相的双极性性质。
Metal chalcogenide thin films have a wide variety of applications and potential uses. Tin(II) sulfide is one such material which presents a significant challenge with the need for high quality SnS, free of oxide materials (e.g., SnO2) and higher tin sulfides (e.g., Sn2S3 and SnS2). This problem is compounded further when the target material exhibits a number of polymorphic forms with different optoelectronic properties. Unlike conventional chemical vapor deposition (CVD) and atomic layer deposition (ALD), which rely heavily on having precursors that are volatile, stable, and reactive, the use of aerosol assisted CVD (AA-CVD) negates the need for volatile precursors. We report here, for the first time, the novel and structurally characterized single source precursor (1), (dimethylamido)(N-phenyl-N',N'-dimethylthiouriate)tin(II) dimer, and its application in the deposition, by AA-CVD, of phase-pure films of SnS. A mechanism for the oxidatively controlled formation of SnS from precursor 1 is also reported. Significantly, thermal control of the deposition process allows for the unprecedented selective and exclusive formation of either orthorhombic-SnS (alpha-SnS) or zinc blende-SnS (ZB-SnS) polymorphs. Thin films of alpha-SnS or ZB-SnS have been deposited onto Mo, fluorine doped tin oxide (FTO), Si, and glass substrates at the optimized deposition temperatures of 375 and 300 degrees C, respectively. The densely packed polycrystalline thin films have been characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, Raman spectroscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy analysis. These data confirmed the phase purity of the SnS formed. Optical analysis of the alpha-SnS and ZB-SnS films shows distinctly different optical properties with direct band gaps of 1.34 and 1.78 eV, respectively. Furthermore, photoelectrochemical and external quantum efficiency (EQE) measurements were undertaken to assess the optoelectronic properties of the deposited samples. We also report for the first time the ambipolar properties of the ZB-SnS phase.