Effect of substrate temperature on microstructure and optical properties of Ga doped ZnO films deposited by pulsed laser deposition

Gallium doped ZnO (GZO) films were deposited on Si (100) and fused silica substrates by pulsed laser deposition at substrate temperature varying from 300 and 600 degrees C. The crystal structure of the deposited film is found to be c axis preferred orientation. The X-ray diffraction results demonstrate that the crystallinity of GZO film is improved and then deteriorated when substrate temperature increases from 300 to 600 degrees C. The average surface roughness slightly decreases from 7.2 to 5.0 nm then increases to 15.6 nm as the substrate temperature reaches 600 degrees C. The optical band gap of the film is found to increase slightly from 3.28 to 3.33 eV with increasing substrate temperature from 300 to 600 degrees C. The refractive index of the GZO film first increases as the substrate temperature increases from 300 to 400 degrees C then decreases when further increases the substrate temperature to 600 degrees C, and is in the range of 1.87-2.23.