Highly conductive and transparent aluminum-doped zinc oxide thin films deposited on polyethylene terephthalate substrates by pulsed laser deposition

• Published in: Thin solid films Vol. 545; pp. 285 - 290
• Main Authors: Wong, L.M., Chiam, S.Y., Chim, W.K., Pan, J.S., Wang, S.J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 31-10-2013; Elsevier
• Subjects: Aluminum; Aluminum zinc oxide; AZO; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deposition; Electrical properties of specific thin films; Electrical resistivity; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Film thickness; Laser deposition; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; PLD; Polyethylene terephthalate; Polyethylene terephthalates; Pulsed laser deposition; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); TCO; Thickness dependence; Thin film structure and morphology; Thin films; Transparent conducting oxide; Zinc oxide; TCO; Thickness dependence; AZO; Polyethylene terephthalate; PLD; Pulsed laser deposition; Aluminum zinc oxide; Transparent conducting oxide; Grain size; Polyethylenes; Transparency; Electrical conductivity; Zinc additions; Layer thickness; Transmittance; Terephthalates; Thin films; Interfaces; Size effect; Zinc oxide; Laser ablation technique; Carrier mobility
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2013.08.069

Highly transparent and conductive aluminum-doped zinc oxide thin films were deposited on low-cost flexible polyethylene terephthalate substrates at room temperature using pulsed laser deposition and the effects of oxygen pressure and film thickness on film properties were investigated. It was found that grain sizes play a greater role only at smaller film thicknesses in affecting carrier mobility. Resistivity changes at larger film thickness can be caused by near surface/interface depletion that affected both mobility and carrier concentration. The inherent film transparency did not change and any reduction in the film transmittance is likely related to a thickness dependent attenuation effect. This means that different transparent conducting oxides should each possess an optimum film thickness, whereby optimized zinc oxide is typically about 100nm. A low resistivity of ~6.6×10−4Ωcm with a high normalized transparency index of >0.9 for a 110±10nm thick room-temperature deposited film was obtained, representing one of the best results obtained to date.
•Room temperature deposition of aluminum-doped zinc oxide (AZO) is studied.•Influence of oxygen pressure and film thickness is examined.•A low resistivity of ~6.6×10−4Ωcm is achieved on flexible substrate.•The optimized AZO film (~100nm) has a high normalized transparency index of 0.90.•A modified figure of merit is shown to include effect of thickness on transmission.