General Electric Company

William W Piper

George E Possin

Harold G Parks

Donald E Castleberry

Jack D Kingsley

John Anthony DeLuca

Jacob Charles Bortscheller

Jerome S Prener

George R Gillooly

A thin film FET switching element, particularly useful in liquid crystal displays (LCDs) employs particular materials and is fabricated via a particular process to ensure chemical compatibility and the formation of good electrical contact to an amorphous silicon layer while also producing FETs with desirable electrical properties for LCDs. These materials include the use of titanium as a gate electrode material and the use of N.sup.+ amorphous silicon as a material to enhance electrical contact between molybdenum source and drain pads and an underlying layer of amorphous silicon. The process of the present invention provides enhanced fabrication yield and device performance.

N.sup.+ amorphous silicon thin film transistors for matrix addressed

A thin film FET switching element, particularly useful in liquid crystal displays, employs a set of special materials to ensure compatibility with the indium tin oxide of a pixel electrode layer used as transparent conductive material in liquid crystal display devices. These materials include the use of titanium as a gate electrode material and the use of aluminum as a material to enhance electrical contact between source and drain pads and an underlying layer of amorphous silicon. The apparatus and process of the present invention provide enhanced fabrication yield and device reliability.

Process and structure for thin film transistor with aluminum contacts

Thin film transistor with aluminum contacts and nonaluminum metallization

A pixel electrode arrangement for use in color liquid crystal display devices provides that on every other row the color filter pixels and their associated transparent electrodes are split symmetrically by the data drive line. Data voltages are supplied to the split electrode pair either by two FETs or by an appropriately insulated conductive bridge extending between split electrode pads. The configuration provided exhibits the advantages inherent in a staggered triad color arrangement without the penalty of decreased data bus pitch or of increased bus overlap. Furthermore, the fraction of the total display area utilized by transmitted light is maintained at a high fraction of the total display area.

Pixel configuration to achieve a staggered color triad with insulated

A process for the fabrication of thin film field effect transistors in active matrix liquid crystal display devices includes the utilization of a protective, conductive tab disposed on a corner portion of the pixel electrodes. Electrical contact is made to the pixel electrodes not directly, but rather through a via opening in protective, insulative and amorphous silicon layers. The structure is particularly advantageous in that it permits the utilization of a wider range of gate and upper level metallization materials, particularly aluminum, whose etchants are otherwise found deleterious to pixel electrode material such as indium tin oxide. The structure of the present invention is seen to be readily fabricatable in accordance with high yield fabrication procedures.

Protective tab structure for use in the fabrication of matrix addressed

An organic or inorganic base solution is employed as a means for passivating the back channel region of an amorphous silicon FET device following plasma etching of the back channel region. The passivation provided significantly reduces back channel leakage currents resulting in FET devices which are compatible with conventional processing methods and which exhibit desirable properties for use in liquid crystal display systems.

Method for passivating the back channel of amorphous silicon field

An amorphous silicon thin film FET is doped and structured to be particularly useful for use in liquid crystal display circuits. In particular, critical FET dimensions are provided along with doping levels and locations which permit optimal reduction of source to gate capacitance, while at the same time, preventing the occurrence of large contact voltage drops. Critical dimensions include active channel length, source-gate overlap, and amorphous silicon thickness. A critical relationship is established amongst these parameters and amorphous silicon doping levels.

Doping for low capacitance amorphous silicon field effect transistor

In a thin film field-effect transistor, source and drain electrodes each include at least one, respective, narrowed, elongated portion. These elongated source and drain portions are oriented in parallel and in adjacent relation to each other, and a respective, complete longitudinal section of each elongated portion overlays a gate electrode. The resulting FET may be fabricated with readily-achievable photolithographic alignment precision as between the source and drain electrode configuration and the gate electrode, and achieves acceptably low source-to-gate and drain-to-gate parasitic capacitances.

Thin film field-effect transistors with tolerance to electrode

A fluorescent lamp construction is described utilizing a particular combination of two different phosphor materials in order to produce more efficient emission of white color light and whose color temperature can be controlled. The particular phosphor combination can be utilized as a blended mixture; and the color point of the lamp emission can be adjusted to approximate black body radiation emission such as incandescent lamp emission with negligible loss in optimum luminous efficacy.

Fluorescent lamp utilizing phosphor combination

An improved cool-white fluorescent lamp utilizes a particular two-component phosphor combination exhibiting a narrow 'blue' emission spectrum and a broad 'yellow' emission spectrum to achieve improved luminous efficacy. In one preferred embodiment, the combination is a blended mixture of europium activated strontium chlorapatite with manganese and antimony coactivated calcium fluorapatite phosphors.

Cool-white fluorescent lamp with phosphor having modified spectral

A fluorescent lamp having a phosphor layer for converting radiation at a first non-visible wavelength to radiation in the visible spectrum, includes a second phosphor layer for converting other non-visible radiation, having a deleterious effect (depreciation) on the first phosphor layer, to wavelengths in the region containing the first wavelength for subsequent conversion to visible light, thus increasing the brightness of the fluorescent lamp simultaneous with minimization of early depreciation of lamp brightness.

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Scotia, NY, United States of America

William W Piper