Impact of the RF Power on the Copper Nitride Films Deposited in a Pure Nitrogen Environment for Applications as Eco-Friendly Solar Absorber.

This material can be considered to be an interesting eco-friendly choice to be used in the photovoltaic field. In this work, we present the fabrication of Cu 3 N thin films by reactive radio-frequency (RF) magnetron sputtering at room temperature, using nitrogen as the process gas. Different RF power values ranged from 25 to 200 W and gas pressures of 3.5 and 5 Pa were tested to determine their impact on the film properties. The morphology and structure were exhaustively examined by Atomic Force Microscopy (AFM), Fourier Transform Infrared (FTIR) and Raman Spectroscopies and X-ray Diffraction (XRD), respectively. The AFM micrographs revealed different morphologies depending on the total pressure used, and rougher surfaces when the films were deposited at the lowest pressure; whereas FTIR and Raman spectra exhibited the characteristics bands related to the Cu-N bonds of Cu 3 N. Such bands became narrower as the RF power increased. XRD patterns showed the (100) plane as the preferred orientation, that changed to (111) with the RF power, revealing a worsening in structural quality. Finally, the band gap energy was estimated from transmission spectra carried out with a Perkin Elmer 1050 spectrophotometer to evaluate the suitability of Cu 3 N as a light absorber. The values obtained demonstrated the capability of Cu 3 N for solar energy conversion applications, indicating a better film performance under the sputtering conditions 5.0 Pa and RF power values ranged from 50 to 100 W.