Preparation and characterization of undoped ZnO TCO films by electron-beam evaporation and activated plasma deposition techniques

Undoped zinc oxide thin films have been deposited on soda lime glass substrates by electron beam evaporation with argon plasma assistance and activated plasma deposition techniques. These methods offer the advantage of low-ion damage, low deposition temperature and large area deposition. The films are transparent (>85% optical transmittance) in the near UV-VIS and near IR ranges. Energy band gap and refraction index were obtained from optical measurements and are near to reported values on literature. The thicknesses were measured using a Dektak profilometer and calculated using optical data. X-ray diffraction analysis indicates that the crystallites of both e-beam evaporated and deposited by plasma activated deposition thin films are preferentially oriented along the c-axis, [0 0 2] direction of the hexagonal crystal structure. The resistivity of ZnO film deposited by plasma activated deposition was 3.1 × 10^-2 ¿.cm, lower than e-beam evaporated film. The films prepared have good optical and structural properties and are a promising TCO material for solar cells applications.