Study on physical properties of indium-doped zinc oxide deposited by spray pyrolysis technique

Transparent conducting indium doped zinc oxide (IZO) thin films have been deposited on soda-lime glass substrates by the spray pyrolysis technique. The structural, electrical, and optical properties of these films were investigated as a function of substrate temperature. In this work the substrate temperature was varied between 350 °C and 500 °C. X-ray diffraction pattern reveals that at 350 °C dominant peak is (100) orientation. By increasing substrate temperature from 350 °C to 450 °C, sheet resistance decreases, from 302 Ω/□ to 26 Ω/□, then at 500 °C increases to 34 Ω/□. In the useful range for deposition (i.e. 450 °C to 500 °C), the orientation of the films was predominantly (002). The lowest sheet resistance (26Ω/□) is obtained at substrate temperature of about 450 °C with the transmittance of about 75%. Study of scanning electron microscopy images shows that films deposited at 400 °C, have grain size as large as 574 nm, while with increasing substrate temperature to 450 °C, grain size becomes smaller and reaches to a value of about 100 nm with spherical shape. At 500 °C grain size value would be around 70 nm with the same spherical shape.