Environmental effects on the electrical behavior of pentacene thin-film transistors with a poly(methyl methacrylate) gate insulator

• Published in: Organic electronics Vol. 14; no. 9; pp. 2101 - 2107
• Main Authors: Park, Jaehoon, Do, Lee-Mi, Bae, Jin-Hyuk, Jeong, Ye-Sul, Pearson, Christopher, Petty, Michael C.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.09.2013; Elsevier
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Electronics; Environmental stability; Exact sciences and technology; Molecular electronics, nanoelectronics; Organic thin-film transistor; Pentacene; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Solid surfaces and solid-solid interfaces; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Transistors; Pentacene; Environmental stability; Organic thin-film transistor; Voltage threshold; Air environment; Insulator; Gate voltage; Electrical properties; Dielectric materials; Permeation; Methyl methacrylate polymer; Drain; Adsorption; Drain current; Diffusion process; Environmental effect; Instability; Top contact configuration; Thin film transistor; Interface; Electrical characteristic; Organic electronics; Charge carrier injection
• ISSN: 1566-1199; 1878-5530
• DOI: 10.1016/j.orgel.2013.05.009

[Display omitted] •Environmentally-induced characteristic variations in pentacene thin-film transistors.•Air molecules act distinctively at each interface in the transistor.•Environmental stability of pentacene transistors is comprehensively explained.•Interaction between charges and air molecules is described together with a physical model. The electrical properties of top-contact pentacene thin-film transistors (TFTs) with a poly(methyl methacrylate) (PMMA) gate dielectric were analyzed in air and vacuum environments. Compared to the vacuum case, the pentacene TFT in air exhibited lower drain currents and more pronounced shifts in the threshold voltage upon reversal of the gate voltage sweep direction, together with a decrease in the field-effect mobility. These characteristic variations were explained in terms of two distinctive actions of polar H2O molecules in pentacene TFT. H2O molecules were suggested to diffuse under the source and drain contacts and interrupt the charge injection into the pentacene film, whereas those that permeate at the pentacene/PMMA interface retard hole depletion in and around the TFT channel. The diffusion process was much slower than the permeation process. The degraded TFT characteristics in air could be recovered mostly by storing the device under vacuum, which suggests that the air instability of TFTs is due mainly to the physical adsorption of H2O molecules within the pentacene film.