Conclusions
This work presents the optimization of the sputtering deposition of Cu3N thin films using a N2 pure environment, at RT and at different RF power values with the aim to determine its suitability as optical absorber. XRD patterns reveal a change in the preferred orientation from (100) to (111) as increasing the RF power. Moreover, at RF power of 100 W and above, a polycrystalline structure with the presence of several weak diffraction peaks are obtained. From the chemical point of view, FTIR and Raman measurements confirmed the presence of Cu-N bonds. From AFM images, it is observed that thin films prepared at low RF power and 3.5 Pa show very smooth surfaces. Finally, the direct and indirect band gap values calculated are suitable for solar absorbers. Hence, these results indicate that (i) the magnetron sputtering is an appropriate method to fabricate this kind of material, and (ii) the depositions at low RF power (up to 100 W) and N2 pressures of 3.5 Pa are mainly preferred due to its smoother surfaces, its stoichiometry closer to the required one, and suitable band gap energies that permit to use this material as a potential absorber substitute of silicon.
Acknowledgements
This research has been supported by Grants PID2019-109215RB-C42 and PID2019-109215RB-C43 funded by MCIN/AEI/ 10.13039/501100011033. M.A. Rodríguez-Tapiador also acknowledge partial funding through MEDIDA C17.I2G: CIEMAT. Nuevas tecnologías renovables híbridas, Ministerio de Ciencia e Innovación, Componente 17 “Reforma Institucional y Fortalecimiento de las Capacidades del Sistema Nacional de Ciencia e Innovación”. Medidas del plan de inversiones y reformas para la recuperación económica funded by the European Union – NextGenerationEU. The authors would also like to thank A. Soubrie from Centro de Microscopía Electrónica “Luis Bru” for her advice and AFM measurements. Finally, A.L. Muñoz-Rosas is grateful to SECTEI México for granted postdoctoral fellowship.