Room temperature deposition of homogeneous, highly transparent and conductive Al-doped ZnO films by reactive high power impulse magnetron sputtering

• Published in: Solar energy materials and solar cells Vol. 157; pp. 742 - 749
• Main Authors: Mickan, Martin, Helmersson, Ulf, Rinnert, Hervé, Ghanbaja, Jaafar, Muller, Dominique, Horwat, David
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2016
• Subjects: AZO; Electronic properties; HiPIMS; Thin films; Transparent conducting oxide; Thin films; Electronic properties; HiPIMS; AZO; Transparent conducting oxide
• ISSN: 0927-0248; 1879-3398; 1879-3398
• DOI: 10.1016/j.solmat.2016.07.020

Aluminum doped zinc oxide (AZO) films have been deposited using reactive high power impulse magnetron sputtering (HiPIMS) and reactive direct current (DC) magnetron sputtering from an alloyed target without thermal assistance. These films have been compared in terms of their optical, electrical and structural properties. While both DC and HiPIMS deposited films show comparable transmittance, their electrical properties are significantly improved by the HiPIMS process. The HiPIMS deposited films show a low resistivity down to the order of 10−4Ωcm with a good homogeneity across the substrate, making them potential candidates for electrodes in solar cells. The density of electrons reached up to 11×1020cm−3, making ionized impurities the main scattering defects. This improvement of the film properties can be related to the specific plasma/target interactions in a HiPIMS discharge. This allows the process to take place in the transition mode and to deposit highly conductive, transparent AZO films on large surfaces at low temperature. While the overall oxygen content is above that of stoichiometric ZnO, higher localization of oxygen is found at the interfaces between crystalline domains with substoichiometric composition. •Transparent Al-doped ZnO films of high and homogeneous conductivity have been synthesized at room temperature.•The properties of the films were optimized by using a reactive High Power Impulse Magnetron Sputtering (HiPIMS).•The improved properties have been related to the high instantaneous sputtering rate in HiPIMS.