Optical and electrical properties of Al-doped ZnO thin films by atomic layer deposition

The present work highlights the low temperature deposition of Al-doped ZnO (AZO) thin films by atomic layer deposition (ALD). The effects of Al doping concentration and substrate temperature on structural, electrical and optical properties of AZO thin films have been systematically studied. X-ray diffraction analysis demonstrates that the preferred orientation of AZO thin films alters from (100) to (002) with the increase of both substrate temperature and Al doping concentration, which may affect the electrical property of the AZO. The resistivity of the AZO reduces with increasing the temperature from 160 to 220 degrees C and then remains broadly stable (in the range of 220-260 degrees C), while the resistivity of the AZO thin films exhibits a sharp fall followed by a slow rise with Al concentration increasing from 0 to 3.57 at.% (atom %). The AZO film deposited at substrate temperature of 220 degrees C and Al content of similar to 2.17 at.% shows the lowest resistivity of 8.33 x 10(-4) Omega cm and the high transmittance of similar to 95%, respectively. The work indicates a promising low temperature deposition of AZO thin films as transparent conductive oxide film.