Influence of oxygen and argon flow on properties of aluminum-doped zinc oxide thin films prepared by magnetron sputtering

• Published in: Thin solid films 2014-09, Vol.566, p.32-37
• Main Authors: Zhu, Hua, Wang, Hemei, Wan, Wenqiong, Yu, Shijin, Feng, XiaoWei
• Format: Article
• Language: English
• Subjects: Aluminum; Aluminum-doped zinc oxide; Argon; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Electrical resistivity; Electron, ion, and scanning probe microscopy; Exact sciences and technology; Film thickness; Grain size; Magnetron sputtering; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Nanoscale materials and structures: fabrication and characterization; Other topics in nanoscale materials and structures; Oxygen/argon flow ratio; Physics; Resistivity; Structure and morphology; thickness; Structure of solids and liquids; crystallography; Surface structure; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Thin films; Transmittance; X-ray diffraction; Zinc oxide
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2014.07.021

In this study, the influence of the oxygen/argon (O2/Ar) flow ratio on aluminum-doped zinc oxide (ZAO) films using a Zn1.22Al0.02O1.25 target was investigated systematically. Different samples were obtained by changing the O2/Ar flow ratio from 0.11 to 3. The grain size first decreased and then increased as the O2/Ar flow ratio increased, reaching a minimum size of 8.53nm at a flow ratio of 1. All films showed different average transmittances above 400nm because of different surface structures and film thicknesses; the thickness of films varied from 261 to 897nm. Moreover, the ZAO films exhibited different optical bandgaps between 3.22eV and 3.31eV. The resistivity first increased from 2.1×10−4Ωcm to 350×10−4Ωcm and then decreased to 220×10−4Ωcm with increasing O2/Ar flow ratio. Both the carrier concentration and Hall mobility first decreased from 5.6×1020cm−3 to 0.3×1020cm−3 and from 3.9cm2/Vs to 0.6cm2/Vs, respectively, and then increased to 0.9×1020cm−3 and 1.1cm2/Vs, respectively, with increasing O2/Ar flow ratio. •The aluminum-doped zinc oxide films were prepared by RF-magnetron sputtering.•The average transmittance of the samples was above 89% in the range of 400–900nm.•The films deposited at low oxygen pressure showed low resistivity.•The grain size and thickness of films were studied.