Cu2ZnGe(S1-xSex)4 - The challenge to synthesize single phase material

THIN SOLID FILMS

卷:669

Article; Proceedings Paper

Niedenzu, Sara^1,2  Gurieva, Galina¹  Schorr, Susan^1,2 

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

[2] Free Univ Berlin, Malteserstr 74, Berlin, Germany

关键词: Copper zinc germanium selenide;    Copper zinc germanium sulfide;    Polycrystalline powders;    Solid state reaction;    Wavelength dispersive X-ray spectroscopy;    Chalcogenides;    Secondary phases;   

DOI  :  10.1016/j.tsf.2018.11.039

来源: Elsevier

【 摘 要 】

The variation of the band gap energy in Cu2ZnGeSe4 and Cu2ZnGeS4 from 1.4 eV to 1.7 eV, which is controlled by different S/(S + Se) ratios renders the Cu2ZnGe(S(1-x)Sex)(4) solid solution an interesting material for the application in multi-junction solar cells. Nevertheless, this system has a certain complexity due to the existence of different polymorphs. Cu2ZnGeSe4 crystallizes in the tetragonal kesterite type structure, whereas Cu2ZnGeS4 may crystallize in the tetragonal stannite or the orthorhombic wurtz-stannite type structure, respectively. To gain deeper insights into this complex system a systematic study of the solid solution series Cu2ZnGe(S1-xSex)(4) was performed using polycrystalline material prepared by solid state reaction. The chemical analysis performed by wavelength dispersive X-ray spectroscopy showed remarkable inhomogeneities with different quaternary phases co-existing within one sample. Additionally, a wide variety of binary and ternary secondary phases as well as elemental Ge was observed. The variety of secondary phases is higher in S-rich samples than in Se-rich samples of the solid solution. Thus, synthesis of Cu2ZnGe(S1-xSex)(4) mixed crystals with off-stoichiometric composition is readily accompanied by the formation of various secondary phases making it a difficult task to obtain single phase material.

【 授权许可】

Free