Optical Properties of Reactive RF Magnetron Sputtered Polycrystalline Cu3N Thin Films Determined by UV/Visible/NIR Spectroscopic Ellipsometry: An Eco-Friendly Solar Light Absorber

Copper nitride (Cu3N), a metastable poly-crystalline semiconductor material with reasonably high stability at room temperature, is receiving much attention as a very promising next-generation, earth-abundant, thin film solar light absorber. Its non-toxicity, on the other hand, makes it a very attractive eco-friendly (greener from an environmental standpoint) semiconducting material. In the present investigation, Cu3N thin films were successfully grown by employing reactive radio-frequency magnetron sputtering at room temperature with an RF-power of 50 W, total working gas pressure of 0.5Pa, and partial nitrogen pressures of 0.8 and 1.0, respectively, onto glass substrates. We investigated how argon affected the optical properties of the thin films of Cu3N, with the aim of achieving a low-cost solar light absorber material with the essential characteristics that are needed to replace the more common silicon that is currently in present solar cells. Variable angle spectroscopic ellipsometry measurements were taken at three different angles, 50∘, 60∘, and 70∘, to determine the two ellipsometric parameters psi, ψ, and delta, Δ. The bulk planar Cu3N layer was characterized by a one-dimensional graded index model together with the combination of a Tauc–Lorentz oscillator, while a Bruggeman effective medium approximation model with a 50% air void was adopted in order to account for the existing surface roughness layer. In addition, the optical properties, such as the energy band gap, refractive index, extinction coefficient, and absorption coefficient, were all accurately found to highlight the true potential of this particular material as a solar light absorber within a photovoltaic device. The direct and indirect band gap energies were precisely computed, and it was found that they fell within the useful energy ranges of 2.14–2.25 eV and 1.45–1.71 eV, respectively. The atomic structure, morphology, and chemical composition of the Cu3N thin films were analyzed using X-ray diffraction, atomic force microscopy, and energy-dispersive X-ray spectroscopy, respectively. The Cu3N thin layer thickness, profile texture, and surface topography of the Cu3N material were characterized using scanning electron microscopy.

[1]  A. Katsaggelos,et al.  Complex dielectric function of H-free a-Si films: Photovoltaic light absorber , 2023, Materials Letters.

[2]  J. Bertomeu,et al.  Impact of the RF Power on the Copper Nitride Films Deposited in a Pure Nitrogen Environment for Applications as Eco-Friendly Solar Absorber , 2023, Materials.

[3]  D. Pugliese,et al.  Effect of Argon on the Properties of Copper Nitride Fabricated by Magnetron Sputtering for the Next Generation of Solar Absorbers , 2022, Materials.

[4]  A. Katsaggelos,et al.  Application of the Holomorphic Tauc-Lorentz-Urbach Function to Extract the Optical Constants of Amorphous Semiconductor Thin Films , 2022, Coatings.

[5]  Deposition of Thin Films Materials used in Modern Photovoltaic Cells , 2022, International Journal of Thin Film Science and Technology.

[6]  E. Rauwel,et al.  Surveying the Synthesis, Optical Properties and Photocatalytic Activity of Cu3N Nanomaterials , 2022, Nanomaterials.

[7]  A. Othonos,et al.  p-Type Iodine-Doping of Cu3N and Its Conversion to γ-CuI for the Fabrication of γ-CuI/Cu3N p-n Heterojunctions , 2022, Electronic Materials.

[8]  Z. Zhong,et al.  Toward high efficiency for long-term stable Cesium doped hybrid perovskite solar cells via effective light management strategy , 2021 .

[9]  E. Blanco,et al.  Optical Characterization of H-Free a-Si Layers Grown by rf-Magnetron Sputtering by Inverse Synthesis Using Matlab: Tauc–Lorentz–Urbach Parameterization , 2021, Coatings.

[10]  Md. Abdul Momin,et al.  Optical and Electronic Structural Properties of Cu3N Thin Films: A First-Principles Study (LDA + U) , 2020, ACS omega.

[11]  J. Ruíz-Pérez,et al.  Optical Transmittance for Strongly-Wedge-Shaped Semiconductor Films: Appearance of Envelope-Crossover Points in Amorphous As-Based Chalcogenide Materials , 2020, Coatings.

[12]  E. Blanco,et al.  Spectroscopic ellipsometry study of non-hydrogenated fully amorphous silicon films deposited by room-temperature radio-frequency magnetron sputtering on glass: Influence of the argon pressure , 2020, Journal of Non-Crystalline Solids.

[13]  B. Richards,et al.  Determination of complex optical constants and photovoltaic device design of all-inorganic CsPbBr3 perovskite thin films. , 2020, Optics express.

[14]  B. Richards,et al.  Experimental Determination of Complex Optical Constants of Air‐Stable Inorganic CsPbI3 Perovskite Thin Films , 2020, physica status solidi (RRL) – Rapid Research Letters.

[15]  E. Blanco,et al.  The influence of Ar pressure on the structure and optical properties of non-hydrogenated a-Si thin films grown by rf magnetron sputtering onto room-temperature glass substrates , 2019, Journal of Non-Crystalline Solids.

[16]  A. Jiang,et al.  Preparation, structure, properties, and application of copper nitride (Cu 3 N) thin films: A review , 2018, Journal of Materials Science & Technology.

[17]  David A. Hanifi,et al.  Copper interstitial recombination centers in Cu3N , 2018, Physical Review B.

[18]  E. Blanco,et al.  Insights into the annealing process of sol-gel TiO 2 films leading to anatase development: The interrelationship between microstructure and optical properties , 2018 .

[19]  E. Blanco,et al.  Optical characterization of amine-solution-processed amorphous AsS2 chalcogenide thin films by the use of transmission spectroscopy , 2017 .

[20]  Andriy Zakutayev,et al.  Design of nitride semiconductors for solar energy conversion , 2016 .

[21]  H. Hosono,et al.  Controlled bipolar doping in Cu3N (100) thin films , 2014 .

[22]  K. Tanaka Minimal Urbach energy in non-crystalline materials , 2014 .

[23]  M. Karimipour,et al.  The effect of pressure on the physical properties of Cu3N , 2014 .

[24]  Keiji Tanaka,et al.  Amorphous Chalcogenide Semiconductors and Related Materials , 2011 .

[25]  G. Jellison,et al.  Parameterization of the optical functions of amorphous materials in the interband region , 1996 .

[26]  Weber,et al.  Electronic structure and chemical-bonding mechanism of Cu3N, Cui3NPd, and related Cu(I) compounds. , 1996, Physical review. B, Condensed matter.

[27]  R. Grigorovici,et al.  Optical Properties and Electronic Structure of Amorphous Germanium , 1966, 1966.

[28]  F. Urbach The Long-Wavelength Edge of Photographic Sensitivity and of the Electronic Absorption of Solids , 1953 .

[29]  R. Juza,et al.  Über die Kristallstrukturen von Cu3N, GaN und InN Metallamide und Metallnitride , 1938 .

[30]  Mahaveer K. Jain,et al.  Room temperature growth of high crystalline quality Cu3N thin films by modified activated reactive evaporation , 2015 .

[31]  D. Boerma,et al.  GROWTH, STRUCTURAL AND OPTICAL PROPERTIES OF CU3N FILMS , 2004 .

[32]  G. Cody Urbach edge of crystalline and amorphous silicon : a personal review , 1992 .

[33]  J. Tauc,et al.  Amorphous and liquid semiconductors , 1974 .