Preparation and characterization of Cd-doped ZnO thin films by spin coating method

ABSTRACT

Cd-doped ZnO thin films were deposited on a glass substrate via spin coating techniques. The structural properties of the thin film were studied by X-ray diffractometry. X-ray diffraction data showed that the grown films were oriented in (100) direction with hexagonal wurtzite phase. The average calculated grain size ranged from 10 to 12 nm. The lattice constants of the as-prepared ZnO films were calculated using standard formulae, and the values are arrived as a = 3.25 Å and c = 5.20 Å, which confirm the hexagonal of the materials. The Scanning Electron Microscope (SEM) images reveal the polycrystalline structure of pure ZnO film. The minimum thickness is found to be 0.7 µm and the maximum is 1.4 µm. The FT-IR spectroscopy shows some absorption bands at 1427.32 cm⁻¹ corresponding to the stretching vibration of C–O band. Various absorption band peaks in the range of 3350–3450 cm⁻¹ correspond to O–H species. From the UV spectral analysis, the band gap of ZnO film coated over a glass substrate is found to be 3.4 eV, the band gap of pure ZnO film is calculated as 3.44 eV, and that of Cd-doped ZnO film for 2, 4, and 6 wt% was 3.43, 3.429, and 3.423 eV respectively.

KEYWORDS:

• Cd-doped ZnO thin film
• X-ray diffractometry
• FT-IR
• SEM
• spin coating technique