p-Type conducting transparent characteristics of delafossite Mg-doped CuCrO 2 thin films prepared by RF-sputtering.
11 November 2015
The growth of technologically relevant compounds, Mg-doped CuCrO2 delafossite thin films, on a quartz substrate by radio-frequency sputtering is reported in this work. The deposition, performed at room temperature, leads to a nanocrystalline phase with extremely low roughness and high density. Delafossite characteristic diffraction peaks were obtained as a function of the thermal treatment under primary vacuum.
The electrical conductivity was optimized until 1.6 S cm−1 with an optical transmittance of 63% in the visible range by a 600 °C annealing treatment under primary vacuum applied for 4 h. The transport properties were analyzed by Seebeck and Hall measurement, integrated spectrophotometry and optical simulation. These measurements highlighted degenerated semiconductor behavior using a hopping mechanism with a high hole concentration (1021 cm−3) and a low mobility (0.2 cm2 V−1 s−1).
The direct optical bandgap of 3.3 eV has been measured according to Tauc's relationship. A refractive index of 2.3 at a wavelength of 1100 nm has been determined by spectroscopic ellipsometry and confirmed by two independent modellings of the optical transmittance and reflectance spectra. All these p-type TCO optoelectronic characteristics have led to the highest Haacke's figure of merit (1.5 × 10−7 Ω−1) reported so far for such delafossite materials.
Barnabé, A., Thimont, Y., Lalanne, M., Presmanes, L. and Tailhades, P., 2015. p-Type conducting transparent characteristics of delafossite Mg-doped CuCrO 2 thin films prepared by RF-sputtering. Journal of Materials Chemistry C, 3(23), pp.6012-6024.
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Category: Solar & Photovoltaics