Tuning of optical properties of CdSₓSe₁₋ₓ thin films using homoleptic cadmium complexes containing [iPr₂P(X)NC(Y)NC₅H₁₀]⁻ ligands as precursors by AACVD dual source approach

High quality CdSₓSe₁₋ₓ thin films were deposited by Aerosol Assisted Chemical Vapor Deposition (AACVD) at 450 °C using the dual source approach on quartz substrates. Cd mole solutions of C₁:C₂ and C₃:C₄ homoleptic precursors, [Cd(iPr₂P(X)NC(Y)NC₅H₁₀-κ2-X,Y)₂] with X = Y = S (C₁); X = Se, Y = S (C₂); X = S, Y = O (C₃) and the dinuclear complex [Cd(iPr₂P(Se)NC(O)NC₅H₁₀-κ2-Se,O)₂(μ₂-O)]₂ (C₄), were used to deposit two sets of thin films, 2F–6F and 7F–9F, respectively. The morphology was studied by scanning electron microscopy (SEM), showing uniform deposition of the materials over the whole film with spherical particles assembled in columns for 2F–5F and 7F, while 8F–9F films showed dense flake-like structures. The elemental composition was confirmed by energy dispersive X-ray analysis (EDXA), revealing additional homogeneous P content between 2.5 % and 7.5 %. The grazing incidence X-Ray diffraction (GIXRD) patterns revealed (002) orientated hexagonal phase formation. Optical properties of the two series of CdSₓSe₁₋ₓ solid solutions were evaluated by UV–Vis, photoluminescence (PL) and Raman spectroscopy. The band gap of the CdSₓSe₁₋ₓ solid solutions could be tuned in the visible region ranging from 1.77 eV to 2.50 eV for set 1, and from 1.74 eV to 2.44 eV for set 2 with x varying from 0 to 1. PL spectra showed composition-dependent near band edge emission (NBE) within the range of 1.69–2.45 eV and 1.63–2.42 eV for sets 1 and 2, respectively. Raman spectra of both series exhibited the expected CdS-like and CdSe-like LO phonons, reveling a linear composition-dependence.