News Column

Patent Issued for Thin Film Transistor Including a Nanoconductor Layer

June 4, 2014

By a News Reporter-Staff News Editor at Electronics Newsweekly -- Ignis Innovation Inc. (Waterloo, Ontario, CA) has been issued patent number 8729529, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

The patent's inventors are Chaji, Gholamreza (Waterloo, CA); Moradi, Maryam (Melrose, IL).

This patent was filed on August 1, 2012 and was published online on May 20, 2014.

From the background information supplied by the inventors, news correspondents obtained the following quote: "Displays can be created from an array of organic light emitting devices ('OLEDs') each controlled by individual circuits (i.e., pixel circuits) having transistors for selectively controlling the circuits to be programmed with display information and to emit light according to the display information. Thin film transistors ('TFTs') fabricated on a substrate can be incorporated into such displays.

"Mobility characterizes the responsiveness of a charge carrier in the presence of an electric field. Mobility is generally expressed in units of cm.sup.2/V s. For transistors, the mobility of the channel region provides a measure of the performance of the transistor 'on' current, e.g., the current that can be supplied by the transistor. In thin film transistors, a layer of semiconductor material is generally utilized to form the channel region.

"Development of OLED display devices is challenged by the demand for a suitable drive transistor in the pixel circuits. Amorphous silicon (a-Si), the transistor channel material that sources the voltage to switch AM-LCD pixels, has a low mobility (.about.0.1 cm.sup.2 V.sup.-1 s.sup.-1). Organic semiconductor channel materials are attractive for use as pixel circuit drive transistors for their homogeneity, low cost, and the variety of means by which they can be deposited, but their best mobilities are similar to that of a-Si. In a typical TFT architecture, low-mobility channel layers would require a large source-drain voltage to drive the necessary current. This consumes power in the transistor (as opposed to light production in the OLED), compromising the power savings.

"P-type a-Si TFTs can have even lower mobility values, and can be as low as 0.01 cm.sup.2V.sup.-1s.sup.-1."

Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "Aspects of the present disclosure provide a thin film transistor ('TFT') suitable for use as an organic light emitting diode ('OLED') drive transistor in a pixel circuit for a display. The TFT includes a channel region having two layers: a semiconductor layer and a nanoconductor layer. The nanoconductor layer can be a dispersed monolayer of nanotubes and/or nanowires formed of carbon. The individual nanoconductors in the nanoconductor layer are generally aligned along a direction oriented from the drain terminal to the source terminal. The nanoconductor layer is separated from both the drain terminal and the source terminal by the semiconductor layer. Thus the nanoconductor layer is generally situated between the semiconductor layer and a dielectric layer on the gate terminal.

"In operation of the TFT, the effective mobility is enhanced. During high field effect operation (e.g., high gate-source voltages), the charge transfer characteristics of the channel region is enhanced by charges being conducted through the nanoconductors. For example, charge carriers can be conveyed via the nanoconductors to/from regions of the semiconductor close to the drain/source terminals of the TFT. Thus, the ability to convey charge carriers within the semiconductor region is supplemented by the nanoconductors. However, during low field effect operation (e.g., low gate-source voltages), the performance of the TFT is dominated by the semiconductor layer because the nanoconductors lack any direct contact with the source or drain terminal of the TFT. Thus, the TFT offers good leakage current performance.

"The foregoing and additional aspects and embodiments of the present invention will be apparent to those of ordinary skill in the art in view of the detailed description of various embodiments and/or aspects, which is made with reference to the drawings, a brief description of which is provided next."

For the URL and additional information on this patent, see: Chaji, Gholamreza; Moradi, Maryam. Thin Film Transistor Including a Nanoconductor Layer. U.S. Patent Number 8729529, filed August 1, 2012, and published online on May 20, 2014. Patent URL:

Keywords for this news article include: Electronics, Semiconductor, Ignis Innovation Inc..

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Source: Electronics Newsweekly

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