Mixed Oxide Thin Film Transistors for Flexible Displays

2011 2011

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Abstract (summary)

A low temperature amorphous oxide thin film transistor (TFT) backplane technology for flexible organic light emitting diode (OLED) displays has been developed to create 4.1-in. diagonal backplanes. The critical steps in the evolution of the backplane process include the qualification and optimization of the low temperature (200 °C) metal oxide process, the stability of the devices under forward and reverse bias stress, the transfer of the process to flexible plastic substrates, and the fabrication of white organic light emitting diode (OLED) displays.

Mixed oxide semiconductor thin film transistors (TFTs) on flexible plastic substrates typically suffer from performance and stability issues related to the maximum processing temperature limitation of the polymer. A novel device architecture based upon a dual active layer enables significant improvements in both the performance and stability. Devices are directly fabricated below 200 ºC on a polyethylene naphthalate (PEN) substrate using mixed metal oxides of either zinc indium oxide (ZIO) or indium gallium zinc oxide (IGZO) as the active semiconductor. The dual active layer architecture allows for adjustment in the saturation mobility and threshold voltage stability without the requirement of high temperature annealing, which is not compatible with flexible colorless plastic substrates like PEN. The device performance and stability is strongly dependent upon the composition of the mixed metal oxide; this dependency provides a simple route to improving the threshold voltage stability and drive performance. By switching from a single to a dual active layer, the saturation mobility increases from 1.2 cm2/V-s to 18.0 cm2/V-s, while the rate of the threshold voltage shift decreases by an order of magnitude. This approach could assist in enabling the production of devices on flexible substrates using amorphous oxide semiconductors.

Indexing (details)

Chemical engineering;
Electrical engineering;
Operations research
0542: Chemical engineering
0544: Electrical engineering
0796: Operations research
Identifier / keyword
Applied sciences; Flexible displays; Indium gallium zinc oxide; Manufacturing; Organic light-emitting diodes; Oxide semiconductors; Polyethylene naphthalate
Mixed Oxide Thin Film Transistors for Flexible Displays
Marrs, Michael
Number of pages
Publication year
Degree date
School code
MAI 50/01M, Masters Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
Raupp, Gregory B.; Vogt, Bryan D.
Committee member
Allee, David R.
Arizona State University
Chemical Engineering
University location
United States -- Arizona
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
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