Short-range versus long-range structure in Cu(In,Ga)Se2, Cu(In,Ga)3Se5, and Cu(In,Ga)5Se8

JOURNAL OF ALLOYS AND COMPOUNDS

卷:774

Article

Haubold, Erik⁶  Schoeppe, Philipp¹  Eckner, Stefanie¹  Lehmann, Sebastian^2,7  Colantoni, Ivan^3,8  d'Acapito, Francesco³  di Benedetto, Francesco⁴  Schorr, Susan^2,5  Schnohr, Claudia S.¹ 

[1] Friedrich Schiller Univ Jena, Inst Festkorperphys, Max Wien Pl 1, D-07743 Jena, Germany

[2] Helmholtz Zentrum Berlin Mat & Energie, Hahn Meitner Pl 1, D-14109 Berlin, Germany

[3] ESRF LISA CRG, CNR IOM OGG, 71 Ave Martyrs, F-38043 Grenoble, France

[4] Univ Firenze, Dipartimento Sci Terra, Via La Pira 4, I-50121 Florence, Italy

[5] Free Univ Berlin, Inst Geol Wissensch, Malteserstr 74-100, D-12249 Berlin, Germany

[6] IFW Dresden, Helmholtzstr 20, D-01069 Dresden, Germany

[7] Lund Univ, Div Solid State Phys & NanoLund, S-22100 Lund, Sweden

[8] Dublin Inst Adv Studies, Sch Cosm Phys, Astron & Astrophys Sect, 31 Fitzwilliam Pl, Dublin D02 XF86, Ireland

关键词: Semiconductors;    Atomic scale structure;    EXAFS;    Synchrotron radiation;    Order-disorder effects;    CIGS;   

DOI  :  10.1016/j.jallcom.2018.10.026

来源: Elsevier

【 摘 要 】

The Cu-poor phases Cu(In,Ga)(3)Se(5 )and Cu(In,Ga)(5)Se-8 play an important role both for understanding the Cu-(In,Ga)-Se material system and for growing high-efficiency Cu(In,Ga)Se-2 thin film solar cells. Using extended X-ray absorption fine structure spectroscopy, we have studied the element-specific short-range structure of Cu(In,Ga)Se-2, Cu(In,Ga)(3)Se-5, and Cu(In,Ga)(5)Se-8 alloys spanning the entire compositional range. The materials feature different local atomic arrangements and the element-specific average bond lengths remain nearly constant despite significant changes of the lattice constants with increasing In to Ga ratio and decreasing Cu content. In particular, the average bond lengths of Cu-Se and Ga-Se are almost identical while the average In-Se bond length is significantly longer in all three phases. The distance between lattice sites with mixed site occupation therefore corresponds to the weighted average of different element-specific bond lengths rather than to the individual bond lengths themselves. Furthermore, the increasing number of vacancies with decreasing Cu content lead to both a significant unit cell contraction and a slight bond length expansion. The crystallographic long-range structure and the element-specific short-range structure thus describe different structural aspects that are certainly interrelated but obviously not identical. (C) 2018 Elsevier B.V. All rights reserved.

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