Morphology and band gap controlled AACVD of CdSe and CdSxSe1-x thin films using novel single source precursors: Bis(diethyldithio/diselenocarbamato)cadmium(II)

Abstract Cadmium selenide (CdSe) and cadmium sulfoselenide (CdSxSe1-x) are important semiconductor materials for photovoltaic and other optoelectronic applications. Highly crystalline thin films of CdSe and CdSxSe1-x have been deposited on glass substrates by Aerosol Assisted Chemical Vapour Deposition (AACVD) from bis(diethyldiselenocarbamato)cadmium(II) and a 1:1 and 2:1 mixtures of bis(diethyldiselenocarbamato)cadmium(II) and bis(diethyldithiocarbamato)cadmium(II). Films were characterised by p-XRD, SEM, EDX, Raman spectroscopy, photoluminescence (PL) and UV-vis absorbance spectroscopy. CdSe thin films showed a band gap of 1.73-1.75 eV whereas CdSxSe1-x films at 1.90-2.00 eV depending on the sulphur content in the films. PL emission and UV-vis absorbance spectra showed a clear blue shift for CdSxSe1-x films compared with CdSe. The band gap of CdSSe can be tuned by controlling the sulphur to selenium ratio in the alloy. The texture of the CdSe thin films changed considerably from randomly orientated to perfect rhombohedral crystallites by increasing the concentration of the precursors in the feed solution.