Zn 2 SbN 3-y O y : a new metastable photoactive material Elisabetta Arca 1,2 , Stephan Lany 2 ,Wenhao Sun 3 , Gerbrand Ceder 3 , Andry Zakutayev 2 1 Newcastle University, UK, 2 Materials Science Center, Colorado USA, 3 Lawrence Berkeley National Laboratory, California USA Wurtize (WZ)-derived ternary nitrides are an interesting class of materials for optoelectronic application. A subset of these, constitutes the Zn-based ternary nitrides in wurtzite derived structure. Peculiar to this family of materials is their ability to accommodate large cation off-stoichiometry, but also large anion off-stoichiometry to the extent that these materials might be more appropriately called oxynitrides. An example of this is the Zn 3 MoN 4 -ZnMoN 2 system, where cation off-stoichiometry enables a continuous tuning of the composition between the two end points, while retaining the WZ structure, through a process that we defined as redox-mediatedstabilisation[1]. Most of the cations in the periodic table have been reported to form nitrides as either a monometallic or bimetallic compound. An exception to this rule was represented by antimony: M-Sb-N ternary compounds where Sb is acting as an anion are known, whereas the discovery of a ternary nitride where Sb is acting as a cation is far more recent.In this contribution, I will present the theoretical search for new ternary nitrides which lead to the discovery of the first ternary antimony nitrideZn 2 SbN 3 where antimony is a cation [2]. A data-mined structure prediction (DMSP) algorithm was used to identify the compound and evaluated the stability of the candidate crystal structures by comparing their density functional theory (DFT) formation energies to the competing phases. Combinatorial RF magnetron sputtering was used as growth technique, to enable access to high nitrogen chemical potential and fast screening of deposition conditions. It was found that this metastable compound could be synthesised over a wide range of deposition conditions, showing tunable optical and electrical properties as a function of the Sb content in the cation sub-lattice and growth conditions. The low native n-type conductivity and moderate carrier concentration, coupled with an almost ideal direct band gap (1.7 eV theoretical, ~1.4 eV experimental), make it a promising candidate as a photoactive material. Based on measured values of the ionization potential and the electron affinity, the applicability of this material as a photoactive absorber will be discussed [3]. References 1. Arca E., et. al., Redox-Mediated Stabilization in Zinc Molybdenum Nitrides, J. Am. Chem. Soc., 140, 4293, (2018) 2. Sun W., Bartel C.J., Arca E., et al., A map of the inorganic ternary metal nitrides. Nat. Mater. 18, 732, (2019) 3. Arca E. et al., Zn 2 SbN 3 : growth and characterization of a metastable photoactive semiconductor, Materials Horizons, 6, 1669, (2019)
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