INFLUENCES OF ANNEALING TEMPERATURE ON THE ELECTRICAL AND OPTICAL PROPERTIES OF Na DOPED ZnO THIN FILMS

Abstract

This paper reports on the electrical and optical properties of natrium doped zinc oxide thin films. Transparent Na doped ZnO thin films have been prepared by sol-gel method using zinc acetate dihydrate as a starting material, 2-methoxyethanol as solvent and diethanolamine (DEA) as sol stabilizer. Then followed by mixing with the doping solution, natrium. Film deposition was performed by spin coating technique at spin rate of 3000rpm on quartz substrates. Then the films were annealed at 400°C, 500°C, 600°C, 700°C and 800°C for 60 minutes in hydrogen. The sheet resistance of the layers decreased from 1.4 x 104 Ω/ to 1.1 x 104 Ω/ as the annealing temperature increased from 400 to 800°C. The average optical transmittance values of the annealed films were more than 85% in the visible range. The energy band gap calculated from the transmittance spectra is about 3.25 – 4.30 eV.