The effects of impurity and temperature for transparent conducting oxide properties of Al:ZnO deposited by dc magnetron sputtering

Aluminum-doped zinc oxide films (ZnO:Al) were deposited on Si wafers and glass substrates by dc magnetron sputtering from a ZnO target mixed with 2 wt% Al2O3 for photovoltaic films. The effect of base pressure, additional oxygen, and substrate temperature were studied in detail. By dc magnetron sputtering at room temperature, the resistivity and the average transmittance in visible range was 23 x 10(-3) Omega cm and 77.3%, respectively. And these were improved up to 3.3 x 10(-4) Omega cm and 86% at the substrate temperature of 400 degrees C by high deposition rate and low impurity ambient. The mobility and the carrier concentration were improved by the increased preferred orientation of (002) plane and grain size of film with increasing deposition temperature. This advanced AZO film with good resistivity and transmittance can be expected as the front TCO of thin film solar cells. (C) 2012 Elsevier Ltd. All rights reserved.