SPIN COATED ITO FILMS PREPARED WITH A SOLUTION OF METHANOL: N-PROPYL ALCOHOL (1:1)

Abstract

A sol-gel method for the synthesis of Indium Tin Oxide films on glass substrate and their structural, electrical and optical characterization is presented in this paper. ITO films were deposited at room temperature by spin coating technique using a solution of ITO nano-powder in methanol (CH3OH) n-propyl alcohol (CH3(CH2)2OH) (1:1) solution. The surface morphology of the films was investigated by Fluoroscence Microscope (FM) and the surface smoothness of the films improved after annealing. The electrical resistivity of the films was measured using Van Der Pauw method and the resistivity is found in 10-1 Ω.cm range. The conductivity as well as smoothness of the films was increased with increasing number of layers and heat treatment. Optical transmittance and absorbance of the films were measured by Ultra Violet (UV) spectrophotometer in the wavelength range of 300nm - 800nm. In the visible and infrared range, the films exhibit low absorbance and high optical transmittance. The direct optical band gap (Eg) of the films was calculated using absorption coefficient (α) and the values of Eg is found in the range 3.5 ~ 3.7 eV. The optical band gap is slightly increased after annealing for lower thickness samples due to increased carrier concentration.

Keywords

• ito
• spin coating
• tco
• sol-gel
• solar cell
• band gap