Rapid thermal annealing effect on the spatial resistivity distribution of AZO thin films deposited by pulsed-direct-current sputtering for solar cells applications

Abstract

Room temperature deposited aluminium-doped zinc oxide thin films on glass substrate, using pulsed-DC magnetron sputtering, have shown high optical transmittance and low electrical resistivity with high uniformity of its spatial distribution after they were exposed to a rapid thermal annealing process at 400°C under N2H2 atmosphere. It is particularly interesting to note that such an annealing process of AZO thin films for only 30s was sufficient, on one hand to improve their optical transmittance from 73% to 86%, on the other hand to both decrease their resistivity from 1.7×10−3Ωcm to 5.1×10−4Ωcm and achieve the highest uniformity spatial distribution. To understand the mechanisms behind such improvements of the optoelectronic properties, electrical, optical, structural and morphological changes as a function of annealing time have been investigated by using hall measurement, UV–visible spectrometry, X-ray diffraction and scanning electron microscope imaging, respectively.