The study of transparent semiconducting oxides (TCO) constitutes a large field of research due to its applications as transparent electrodes in transistors, flat panel displays, solar cells, sensors, etc. [1, 2]. Most of the interest is aimed to optimize both conductivity and transparency in the visible region of commercial indium tin oxide (ITO), with lower production costs. In this sense, the In₂Zn_kO_3+k system seems to be one of the best candidates. Moriga et al [3] reported the discovery of nine members in this system. The physical properties of these phases are a function of the k value. Likewise these phases allow doping with other elements, which provides greater flexibility when designing materials [4, 5].

 In this work, In_2-xM_xZn₇O₁₀ (M = Ga and Fe, and 0≤x≤0.5) materials have been prepared by the ceramic method. The k=7 term crystallizes in the space group R-3m, the introduction of dopant decreasing the lattice parameter without changing the crystalline structure. HRTEM images show these materials formed by ordered layers of InO octahedra sharing edges with layers of (InZn_k)O_k+1⁺ composition along c-axis, in such a way that the (001) plane of the ZnO structure and the (111) In₂O₃ plane are epitaxially equivalent to the (001) plane of Zn_kIn₂O_k+3. The existence of extended defects such as twins, dislocations and disordered intergrowths were observed.

Cathodoluminescence (CL) measurements show the existence of two emission bands, one associated to defects whose intensity and width vary depending on the chemical composition of the material. The second issue is the band edge of the material, which is present in the undoped sample, and it disappears and reappears depending on dopant concentrations. EDS spectroscopy confirms the presence of Ga and Fe dopants. A deeper study by means of atomic resolved microscopy has been performed in order to stablish the structure-properties relationship.

References:

[1] C.G. Granqvist, Solar Energy Materials & Solar Cells. 91 (2007) 1529-1598

[2] G.B. Palmer, K.R. Poeppelmeier, T.O. Mason, Chem. Mater .9 (1997) 3121-3126.

[3] T. Moriga, D. D. Edwards, T. O. Mason, G. B. Palmer, K. R. Poepperlmeier, J. L. Schindler, C. R. Kannewurf, I. Nakabayashi, J. Am. Ceram. Soc. 81 (1998) 5, 1310-1316

[4] R. Wang, A. W. Sleight, R. Platzer y J. A. Gardner, J. Solid StateChem. 122, (1996) 166-175.

[5] A. Ambrosini, S. Malo, K. R. Poeppelmeier, M. A. Lane, C. R. Kannewurf y T. O. Mason, Chem. Mater. 14 (2002) 58-63.

« Back to The 16th European Microscopy Congress 2016

EMC Abstracts - https://emc-proceedings.com/abstract/nanostructure-and-luminescence-of-ga-and-fe-doped-izos/