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

Abstract

Copper nitride (Cu3N) has gained significant attention recently due to its potential in several scientific and technological applications. This study focuses on using Cu3N as a solar absorber in photovoltaic technology. Cu3N thin films were deposited on glass substrates and silicon wafers via radio-frequency magnetron sputtering at different nitrogen flow ratios with total pressures ranging from 1.0 to 5.0 Pa. The thin films’ structural, morphology, and chemical properties were determined using XRD, Raman, AFM, and SEM/EDS techniques. The results revealed that the Cu3N films exhibited a polycrystalline structure, with the preferred orientation varying from 100 to 111 depending on the working pressure employed. Raman spectroscopy confirmed the presence of Cu-N bonds in characteristic peaks observed in the 618–627 cm−1 range, while SEM and AFM images confirmed the presence of uniform and smooth surface morphologies. The optical properties of the films were investigated using UV-VIS-NIR spectroscopy and photothermal deflection spectroscopy (PDS). The obtained band gap, refractive index, and Urbach energy values demonstrated promising optical properties for Cu3N films, indicating their potential as solar absorbers in photovoltaic technology. This study highlights the favourable properties of Cu3N films deposited using the RF sputtering method, paving the way for their implementation in thin-film photovoltaic technologies. These findings contribute to the progress and optimisation of Cu3N-based materials for efficient solar energy conversion.

Effects of Deposition Temperature and Working Pressure on the Thermal and Nanomechanical Performances of Stoichiometric Cu3N: An Adaptable Material for Photovoltaic Applications

“…Silicon and glass substrates were Table 6 also shows the Urbach energy values E U obtained from the fits. The transition from Tauc-indirect absorption to Urbach exponential absorption is also supposed to be smooth for a certain transition energy E 1 ; the fitting model assumes that both α(E) and the derivative dα/dE vary continuously for E 1 [41]. The values of energy E 1 are presented in Table 6, along with the values of E For a photovoltaic application, it is essential to consider two key parameters: the direct bandgap and the absorption coefficient at 1 eV.…”

“…An illustration of this spectrum can be found in Figure 7A. From the full spectrum, we determine the most significant optical parameters of Cu 3 N, including band gaps and Urbach energy, by utilizing the model fit described in reference [41].…”

“…However, internal reflections in this case are negligible and it is possible to calculate the absorption coefficient directly from the internal absorbance, Aopt/(1 − Ropt), and the thickness. A detailed procedure description can be found in [41]. Table 6 displays the extracted refractive index values (n ∞ ) from the fits.…”

“…From the values of n ∞ and optical thickness, the absorption coefficient α in the "transparent" zone can be determined by comparing the experimental PDS absorption to that obtained through TMM calculation. In the region of strong absorption, the refractive index showed a significant dependence on the wavelength [41], and the TMM calculation with constant n ∞ is not feasible. However, internal reflections in this case are negligible and it is possible to calculate the absorption coefficient directly from the internal absorbance, A opt /(1 − R opt ), and the thickness.…”

“…This is because the growth parameters can be easily controlled, thus managing the thickness, the deposition rate, and the coating uniformity [34]. Moreover, it is highly flexible [35] and enables the control of key parameters, such as substrate temperature, working pressure, and bias voltage, among others [22,24,32,[36][37][38][39][40][41][42]. Specifically, radiofrequency (RF) magnetron sputtering offers the advantage of generating fewer impurities compared to chemical methods, thus enhancing the material's purity and quality.…”