The dielectric functions and optical band gaps of thin films of amorphous and cubic crystalline Mg∼2NiH∼4

THIN SOLID FILMS

卷:520

Article

Selj, J. H.¹  Mongstad, T.¹  Hauback, B. C.¹  Karazhanov, S. Zh.¹ 

[1] Inst Energy Technol, NO-2027 Kjeller, Norway

关键词: Metal hydride;    Magnesium nickel hydride;    Thin film;    Ellipsometry;    Optical properties;    Structural properties;    Crystallinity;    Band gap estimation;   

DOI  :  10.1016/j.tsf.2012.07.044

来源: Elsevier

【 摘 要 】

Magnesium nickel hydride films have earlier been suggested for several optoelectronic applications, but the optical properties and band gap have not been firmly established. In this work, the dielectric functions and the optical band gaps of thin films of Mg2NiH4 have been determined experimentally from optical modeling using spectroscopic ellipsometry and spectrophotometry in the photon energy range between 0.7 and 4.2 eV. Samples were prepared by reactive sputtering, resulting in a single-layer geometry that could easily be studied by ellipsometry. Crystalline samples were prepared by annealing the as-deposited amorphous films ex-situ. The resulting films remained in the high temperature cubic Mg2NiH4 structure even after cooling to room temperature. Tauc analysis of the dielectric functions shows that Mg2NiH4 films exhibit a band gap of 1.6 eV for the amorphous structure and 2.1 eV for the cubic crystalline structure. (C) 2012 Elsevier B. V. All rights reserved.

【 授权许可】

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