Effect of substrate temperature on the formation of CdO composite in CdS-doped SiO2 films as deposited by PLD

Thin films of CdS-doped SiO2 glass were prepared on silicon substrates by using the conventional pulsed laser deposition (PLD) technique employing a dual-material rotating target. The optical and structural properties of the as-prepared films under various substrate temperatures were analyzed by photoluminescence, atomic force microscopy and X-ray diffraction. The appearance of the satellite CdO sites in the films was found to be closely related to the substrate temperature during deposition. Experimental results showed that the optimum substrate temperature to yield good quality crystalline films free from the CdO sites was between 200°C and 300°C. Although structural crystalline films could also be formed under higher or lower deposition temperatures, they resulted in undesirable stresses in the deposited film which were always accompanied by the formation of CdO. This conclusion optimized one key parameter in PLD technique for the fabrication of our CDG (CdS-doped SiO2) films.