Nanocolumnar CdS thin films grown by glancing angle deposition from a sublimate vapor effusion source

The glancing angle deposition (GLAD) technique was used to grow cadmium sulfide (CdS) thin films on glass and indium tin oxide (ITO)-coated glass substrates from a sublimate vapor effusion source. The samples were prepared under different incident deposition flux angles (α) of 0°, 20° and 80°, while both the substrate and the source were under rotation. The temperature of the source was 923.15K. Scanning electron microscopy images showed that the GLAD method combined with the source produced dense nanocolumnar structures with height and diameters of ∼200 and ∼30nm, respectively. The deposited films displayed a hexagonal structure with preferential (002) plane orientation and crystallites sizes between ∼25nm and ∼35nm. A maximum solar weighted transmission of ∼92% was obtained for the sample prepared at α=80°, with a substrate/source rotation velocity ratio of 55/20 in the wavelength region of 400–900nm. The average band-gap energy of the films was ∼2.42eV. Refractive indexes between ∼1.4 and ∼2.4 at a 550nm the wavelength was also obtained.