Structural investigation of the Cu2Se–In2Se3–Ga2Se3 phase diagram, X-ray photoemission and optical properties of the Cu1−z(In0.5Ga0.5)1+z/3Se2 compounds
Structural investigation of the Cu2Se–In2Se3–Ga2Se3 phase diagram, X-ray photoemission and optical properties of the Cu1−z(In0.5Ga0.5)1+z/3Se2 compounds
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Cu2Se-In2Se3-Ga2Se3 相图的结构研究、Cu1−z(In0.5Ga0.5)1+z/3Se2 化合物的 X 射线光电发射和光学性质
DOI：
10.1016/j.jssc.2010.08.014
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发表时间：
2010
影响因子：
3.3
通讯作者：
M. Evain
中科院分区：
文献类型：
--
作者：
M. Souilah;A. Lafond;C. Guillot;S. Harel;M. Evain
用X射线衍射方法研究了Cu_2Se-In_2Se_3-Ga_2Se_3系统化合物的结构。对所谓化学计量化合物Cu（In，Ga）Se 2（CIGSe）的单晶结构研究证实，黄铜矿结构（空间群I4 <$2d）非常灵活，可以适应Ga取代In。另一方面，当铜空位比（z）增加时，Cu 1 −z（In0.5Ga0.5）1+z/3Se 2系列的结构发生了变化;当z≥0.26时，黄铜矿结构转变为改性的锡铁矿结构（I4 <$2m）。从Cu 0.74（In 0.5Ga 0.5）1.09Se 2到Cu 0.25（In 0.5Ga 0.5）1.25Se 2（即Cu（In 0.5Ga 0.5）5Se 8），包括Cu 0.4（In 0.5Ga 0.5）1.2Se 2（即Cu（In 0.5Ga 0.5）3Se 5），存在结构的连续演变。从这个单晶结构的研究，它是明确的，没有有序的空位化合物存在于该系列。X射线光电子能谱研究首次表明粉末状Cu 1 −z（In0.5Ga0.5）1+z/3Se 2化合物（z <$0）的表面比块体更贫铜。在用于光伏应用的CIGSe薄膜材料上经常观察到相同的结果。此外，当z从0变化到0.75时，这些非化学计量化合物的光学带隙从1.2增加到1.4eV。
Structures of compounds in the Cu2Se–In2Se3–Ga2Se3system have been investigated through X-ray diffraction. Single crystal structure studies for the so-called stoichiometric compounds Cu(In,Ga)Se2(CIGSe) confirm that the chalcopyrite structure (space group I4¯2d) is very flexible and can adapt itself to the substitution of Ga for In. On the other hand a structure modification is evidenced in the Cu1−z(In0.5Ga0.5)1+z/3Se2series when the copper vacancy ratio (z) increases; the chalcopyrite structure turns to a modified-stannite structure (I4¯2m) when z≥0.26. There is a continuous evolution of the structure from Cu0.74(In0.5Ga0.5)1.09Se2to Cu0.25(In0.5Ga0.5)1.25Se2((i.e. Cu(In0.5Ga0.5)5Se8), including Cu0.4(In0.5Ga0.5)1.2Se2(i.e. Cu(In0.5Ga0.5)3Se5). From this single crystal structural investigation, it is definitively clear that no ordered vacancy compound exists in that series. X-ray photoemission spectroscopy study shows for the first time that the surface of powdered Cu1−z(In0.5Ga0.5)1+z/3Se2compounds (z≠0) is more copper-poor than the bulk. The same result has often been observed on CIGSe thin films material for photovoltaic applications. In addition, optical band gaps of these non-stoichiometric compounds increase from 1.2 to 1.4eV when z varies from 0 to 0.75.