A novel and potentially scalable CVD-based route towards SnO2:Mo thin films as transparent conducting oxides
Tianlei Ma, Marek Nikiel, Andrew G. Thomas, M. Missous, David J. Lewis
Abstract
Abstract In this report, we prepared transparent and conducting undoped and molybdenum-doped tin oxide (Mo–SnO 2 ) thin films by aerosol-assisted chemical vapour deposition (AACVD). The relationship between the precursor concentration in the feed and in the resulting films was studied by energy-dispersive X-ray spectroscopy, suggesting that the efficiency of doping is quantitative and that this method could potentially impart exquisite control over dopant levels. All SnO 2 films were in tetragonal structure as confirmed by powder X-ray diffraction measurements. X-ray photoelectron spectroscopy characterisation indicated for the first time that Mo ions were in mixed valence states of Mo(VI) and Mo(V) on the surface. Incorporation of Mo 6+ resulted in the lowest resistivity of $$7.3 \times 10^{{ - 3}} \Omega \,{\text{cm}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>7.3</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> <mml:mi>Ω</mml:mi> <mml:mspace/> <mml:mtext>cm</mml:mtext> </mml:mrow> </mml:math> , compared to pure SnO 2 films with resistivities of $$4.3\left( 0 \right) \times 10^{{ - 2}} \Omega \,{\text{cm}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>4.3</mml:mn> <mml:mfenced> <mml:mn>0</mml:mn> </mml:mfenced> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> <mml:mi>Ω</mml:mi> <mml:mspace/> <mml:mtext>cm</mml:mtext> </mml:mrow> </mml:math> . Meanwhile, a high transmittance of 83% in the visible light range was also acquired. This work presents a comprehensive investigation into impact of Mo doping on SnO 2 films synthesised by AACVD for the first time and establishes the potential for scalable deposition of SnO 2 :Mo thin films in TCO manufacturing. Graphical abstract