Role of ultrathin Al2O3 layer in organic/inorganic hybrid gate dielectrics for flexibility improvement of InGaZnO thin film transistors

• Published in: Organic electronics Vol. 15; no. 7; pp. 1458 - 1464
• Main Authors: Hwang, Byeong-Ung, Kim, Do-Il, Cho, Sung-Won, Yun, Myeong-Gu, Kim, Hak Jun, Kim, Youn Jea, Cho, Hyung-Koun, Lee, Nae-Eung
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.07.2014; Elsevier
• Subjects: a-IGZO; Applied sciences; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Electronics; Exact sciences and technology; Flexible device; Fractures; Hybrid gate dielectrics; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Methods of deposition of films and coatings; film growth and epitaxy; Molecular electronics, nanoelectronics; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Thin film transistors; Transistors; Flexible device; Thin film transistors; Hybrid gate dielectrics; a-IGZO; Polyimide; Amorphous material; Flexibility; Atomic layer epitaxial growth; Finite element method; Nanometer scale; Microelectronic fabrication; III-VI compound; Pyrrolidone(vinyl) polymer; Bending; Electrical characteristic; Damaging; Ultrathin films; Atomic layer method; Nanostructure; Thickness; Organic-inorganic hybrid materials; Phenols; Thin film transistor; Sputter deposition; Alumina; Organic insulators
• ISSN: 1566-1199; 1878-5530
• DOI: 10.1016/j.orgel.2014.04.003

[Display omitted] •The flexible amorphous InGaZnO (a-IGZO) thin film transistors were fabricated.•Stress and strain distributions in the TFT structures were systematically analyzed.•We evaluated characteristics of devices under mechanical deformation. We investigated flexible amorphous InGaZnO (a-IGZO) thin film transistors (TFTs) on a polyimide (PI) substrate by using organic/inorganic hybrid gate dielectrics of poly-4vinyl phenol (PVP) and ultrathin Al2O3. IGZO TFTs were fabricated with hybrid PVP/Al2O3 gate dielectrics having Al2O3 layers of different nanoscale thicknesses, which were deposited by atomic layer deposition (ALD). The electrical characteristics of the TFTs with the organic/inorganic hybrid gate dielectrics were measured after cyclic bending up to 1,00,000 cycles at the bending radius of 10mm. The ultrathin Al2O3 layer in the hybrid gate dielectrics improved the mechanical flexibility and protected the organic gate dielectric against damage during the sputter deposition of the IGZO layer. Finite elements method (FEM) simulations along with the structural characterization of the cyclically bent device showed the importance of optimizing the thickness of the Al2O3 layer in the hybrid gate dielectrics to obtain mechanically stable and flexible a-IGZO TFTs.