Power effect on the properties of copper nitride films as solar absorber deposited in pure nitrogen atmosphere

Abstract

Nowadays, copper nitride (Cu3N) is of great interest as a new solar absorber material, flexible and lightweight thin film solar cells. This material is a metastable semiconductor, nontoxic, composed of earth‐abundant elements, and its band gap energy can be easily tunable in the range 1.4–1.8 eV. For this reason, it has been proposed for many applications in the solar energy conversion field. The main aim of this work is to evaluate the properties of the Cu3N thin films fabricated by reactive radio‐frequency (RF) magnetron sputtering at different RF power values to determine its potential as light absorber. The Cu3N films were fabricated at room temperature from a Cu metallic target at the RF power ranged from 25 to 200 W onto different substrates (silicon and glass). The pure nitrogen flux was set to 20 sccm, and the working pressures were set to 3.5 Pa and 5 Pa. The X‐ray diffraction results showed a transition from (100) to (111) preferred orientations when RF power increased; the atomic force microscopy images revealed a granular morphology, while Fourier transform infrared spectroscopy and Raman spectra exhibited the characteristics peaks related to Cu–N bonds, which became narrower when the RF power increased. Finally, to stablish the suitability of these films as absorber, the band gap energy was calculated from transmission spectra.

Copper Nitride: A Versatile Semiconductor with Great Potential for Next-Generation Photovoltaics

“…This method's ease, simplicity, low cost, reproducibility and sustainability make it a very attractive choice for the growth of Cu 3 N thin films. Previous studies have already reported that by modifying the bias voltage [33], the type of substrate [32], the working pressure [34], and the RF power [35], the film properties can be adjusted, allowing the variation in optical, electrical, structural, and morphological features to suit them to the desired ones depending on the application field. In addition, in our previous works, we have demonstrated the strong effect of RF power on modifying the morphological, structural, and optical Cu 3 N characteristics, intending to use them as solar absorbers for next-generation photovoltaics [19].…”