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DS: Fachverband Dünne Schichten
DS 3: Layer Properties
DS 3.2: Vortrag
Montag, 18. März 2024, 15:30–15:45, A 053
Eliminating oxygen in-diffusion for stabilization of electrical properties in CuI thin films — •Christiane Dethloff, Sofie Vogt, Holger von Wenckstern, and Marius Grundmann — Felix-Bloch-Institut, Universität Leipzig, Deutschland
The p-type semiconductor CuI is of great potential for transparent opto-electronics due to an intrinsic charge carrier density of up to 1020 cm-3 combined with a direct band gap of 2.95 eV at room temperature and high transparency in the visible range [1,2].
The p-type behavior is attributed to Cu vacancies, but recently also to oxygen, which acts as a shallow acceptor. It was demonstrated that in particular ex-situ oxygen diffusion causes an increase of hole density and electrical conductivity, often resulting in degenerate thin films [2].
To access the full potential of CuI and its alloys for semiconductor thin film applications, it is crucial to prevent in-diffusion of oxygen. Although amorphous Al2O3 capping layers atop CuI thin films have already been shown to prolongate deterioration of the electrical properties, the influence of a full encapsulation has not yet been investigated. Therefore, we present completely in-situ encapsulated CuI thin films deposited by magnetron co-sputtering from a Cu target in a reactive iodine and argon atmosphere. We compare the efficiency of Al2O3 and SiNx cappings that encapsulate the surface and the entire layers, respectively. For that, long-term resistivity and Hall effect measurements are performed over several days.
[1] Yang et al. Nat Commun 8, 16076 (2017).
[2] Storm et al. APL Mater. 9 (5): 051101 (2021).
Keywords: copper idode; sputtering; capping layer; oxygen diffusion