Fabrication of Cu₃N thin films on MgO(100) and <i>α</i>-Al₂O₃(0001) substrates by reactive radio frequency magnetron sputtering: a comparative study

Abstract Copper nitride (Cu 3 N) thin films were prepared using the reactive radio frequency (RF) magnetron sputtering method on MgO (100) and α -Al 2 O 3 (0001) substrates and their physical properties were evaluated. Both X-ray diffraction and hall measurement data showed better crystalline quality of the sample grown on α -Al 2 O 3 (0001) substrates [Cu 3 N/ α -Al 2 O 3 (0001)] than on MgO (100) substrates [Cu 3 N/MgO (100)]. Then, the nitrogen gas fraction ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>R</mml:mi> <mml:msub> <mml:mi mathvariant="normal">N</mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:msub> </mml:math> ) effect on Cu 3 N/ α -Al 2 O 3 (0001) was studied by changing the Ar and N 2 gas mixture ratio during the deposition. The full width at half maximum of (100) diffraction peak was the lowest (0.125°) at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>R</mml:mi> <mml:msub> <mml:mi mathvariant="normal">N</mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:msub> </mml:math> = 0.67. The UV–Vis data revealed a large absorption coefficient (&gt;10 4 cm −1 ) for all the samples, with band gaps ranging from 1.90 to 1.98 eV. The lowest resistivity (26 Ω cm) and the highest carrier concentration (6.4 × 10 17 cm −3 ) were observed at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>R</mml:mi> <mml:msub> <mml:mi mathvariant="normal">N</mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:msub> </mml:math> = 0.67. Consequently, Cu 3 N/ α -Al 2 O 3 (0001) exhibited promising results, suggesting potential for developing efficient solar cells.