Abstract: Thin film transistors and arrays having controlled threshold voltage and improved ION/IOFF ratio are provided in this invention. In one embodiment, a thin film transistor having a first gate insulator of high breakdown field with positive fixed charges and a second gate insulator with negative fixed charges is provided; said negative fixed charges substantially compensate said positive fixed charges in order to reduce threshold voltage and OFF state threshold voltage of said transistor. In another embodiment, a thin film transistor having a first passivation layer with negative fixed charges is provided, the negative charges reduce substantially unwanted negative charges in the adjacent active channel and hence reduce the OFF state current and increase ION/IOFF ratio, which in turn reduce the threshold voltage of the transistor.

Abstract: The present invention provides methods for fabricating devices with low resistance structures involving a lift-off process. A radiation blocking layer is introduced between two resist layers in order to prevent intermixing of the photoresists. Cavities suitable for the formation of low resistance T-gates or L-gates can be obtained by a first exposure, developing, selective etching of blocking layer and a second exposure and developing. In another embodiment, a low resistance gate structure with pillars to enhance mechanical stability or strength is provided.

Abstract: This invention provides a bifacial photovoltaic device to enhance the conversion of solar energy into electricity with a layer by layer additive structure. The bifacial photovoltaic device comprises an electrically conductive core electrode, a plurality of semiconductor layers covering one end region of the core electrode and at least a portion of the two faces of the core electrode, a first counter electrode, a second counter electrode, and a third counter electrode connecting the first and the second counter electrodes. The device may also comprise a light reflective layer and an anti-reflective layer. This invention also provides an array of bifacial photovoltaic cells with simple interconnection schemes.

Abstract: Thin film transistors and arrays having controlled threshold voltage and improved ION/IOFF ratio are provided in this invention. In one embodiment, a thin film transistor having a first gate insulator of high breakdown field with positive fixed charges and a second gate insulator with negative fixed charges is provided; said negative fixed charges substantially compensate said positive fixed charges in order to reduce threshold voltage and OFF state threshold voltage of said transistor. In another embodiment, a thin film transistor having a first passivation layer with negative fixed charges is provided, the negative charges reduce substantially unwanted negative charges in the adjacent active channel and hence reduce the OFF state current and increase ION/IOFF ratio, which in turn reduce the threshold voltage of the transistor.

Abstract: Thin film transistors and circuits having improved mobility and stability are disclosed in this invention to have metal oxynitrides as the active channel layers. In one embodiment, the charge carrier mobility in the thin film transistors is increased by using the metal oxynitrides as the active channel layers. In another embodiment, a thin film transistor having a p-type metal oxynitride active channel layer and a thin film transistor having an n-type metal oxynitride active channel layer are fabricated to forming a CMOS circuit. In yet another embodiment, thin film transistor circuits having metal oxynitrides as the active channel layers are provided.

Abstract: This invention provides a bifacial photovoltaic device to enhance the conversion of solar energy into electricity with a layer by layer additive structure. The bifacial photovoltaic device comprises an electrically conductive core electrode, a plurality of semiconductor layers covering one end region of the core electrode and at least a portion of the two faces of the core electrode, a first counter electrode, a second counter electrode, and a third counter electrode connecting the first and the second counter electrodes. The device may also comprise a light reflective layer and an anti-reflective layer. This invention also provides an array of bifacial photovoltaic cells with simple interconnection schemes.

Abstract: Photonic Band Gap (PBG) structures are utilized in microwave components as filters to suppress unwanted signals because they have the ability to produce a bandstop effect at certain frequency range depending on the structural dimensions. The unique property of PBG structures is due to the periodic change of the dielectric permittivity so interferences are created with the traveling electromagnetic waves. Such periodic arrangement could exist either inside of the dielectric substrate or in the ground plane of a microstrip transmission line structure. This invention provides tunable or switchable planar PBG structures, which contains lattice pattern of periodic perforations inside of the ground plane. The tuning or switching of the bandstop characteristics is achieved by depositing a conducting island surrounded by a layer of controllable thin film with variable conductivities.

Abstract: In electronic displays or imaging units, the control of pixels is achieved by an array of transistors. These transistors are in a thin film form and arranged in a two-dimensional configuration to form switching circuits, driving circuits or even read-out circuits. In this invention, thin film transistors and circuits with indium oxide-based channel layers are provided. These thin film transistors and circuits may be fabricated at low temperatures on various substrates and with high charge carrier mobilities. In addition to conventional rigid substrates, the present thin film transistors and circuits are particularly suited for the fabrication on flexible and transparent substrates for electronic display and imaging applications. Methods for the fabrication of the thin film transistors with indium oxide-based channels are provided.

Abstract: Organic semiconductor-based devices such as thin film transistors, organic light emitting devices and solar cells have potential in low cost electronic and optoelectronic applications. The performance of these organic semiconductor-based devices is often limited by the large resistance between the organic semiconductors and counter electrodes. This invention provides device structures and methods to reduce the unwanted resistance.

Abstract: Organic semiconductor-based devices such as thin film transistors, organic light emitting devices and solar cells have potential in low cost electronic and optoelectronic applications. The performance of these organic semiconductor-based devices is often limited by the large resistance between the organic semiconductors and counter electrodes. This invention provides device structures and methods to reduce the unwanted resistance.

Abstract: In electronic displays or imaging units, the control of pixels is achieved by an array of transistors. These transistors are in a thin film form and arranged in a two-dimensional configuration to form switching circuits, driving circuits or even read-out circuits. In this invention, thin film transistors and circuits with indium oxide-based channel layers are provided. These thin film transistors and circuits may be fabricated at low temperatures on various substrates and with high charge carrier mobilities. In addition to conventional rigid substrates, the present thin film transistors and circuits are particularly suited for the fabrication on flexible and transparent substrates for electronic display and imaging applications. Methods for the fabrication of the thin film transistors with indium oxide-based channels are provided.

Abstract: Photonic Band Gap (PBG) structures are utilized in microwave components as filters to suppress unwanted signals because they have the ability to produce a bandstop effect at certain frequency range depending on the structural dimensions. The unique property of PBG structures is due to the periodic change of the dielectric permittivity so interferences are created with the traveling electromagnetic waves. Such periodic arrangement could exist either inside of the dielectric substrate or in the ground plane of a microstrip transmission line structure. This invention provides tunable or switchable planar PBG structures, which contains lattice pattern of periodic perforations inside of the ground plane. The tuning or switching of the bandstop characteristics is achieved by depositing a conducting island surrounded by a layer of controllable thin film with variable conductivities.

Abstract: A method for fabricating a thin film field effect transistor is described in this invention. The active layer of the thin film transistor (TFT) is formed by a low cost chemical bath deposition method. The fabrication procedure includes deposition of a metal layer on an insulating substrate, patterning of the metal layer to form a metal gate, formation of the di-electric layer, deposition of the active layer and formation of source and drain contacts.

Abstract: Methods for wavelength determination of a monochromatic light beam are described. The methods involve a detector unit containing at least one pair of photo detectors. One of the detectors in each detector pair is covered with a variable attenuator and the other is not covered by the variable attenuator. The optical transmission coefficient of the variable attenuator is a monotonic function of wavelength. Under illumination of a monochromatic light, the photocurrents produced in the detectors with and without the variable attenuator are compared. The relative values of the photocurrents are used to determine the wavelength of the monochromatic light.

Abstract: Methods of forming a field emission device with self-aligned gate structure, comprising a substrate on which at least one wedge or tip electrode and one accelerating or gate electrode are provided. The only photolithographic step involved is to pattern an integrated gate electrode opening on high quality, thermally grown oxide which can withstand a strong electric field. The formation of the emissive electrode by etching starts at the edge of the integrated gate electrode opening defined by the oxide material layer. As a result, the distance between the emissive electrode and the gate electrode is minimum. Simple wet chemical etching may be used to form the emissive electrode.

Abstract: Methods for wavelength determination of a monochromatic beam are described. The methods involve a detector unit containing at least one variable filter and at least one pair of photo detectors. The detectors have photo sensitive regions with their areas varying with the position in one direction. The wavelength for maximum transmission of the variable filter varies in the same direction. By comparing the photo current values from the two detectors, wavelength of the incident beam is determined. Methods to construct wavelength discrimination junction photo detector pair and double barrier photo detector pair are also given.

Abstract: Methods for wavelength determination of a monochromatic beam are described. The methods involve a detector unit containing at least one variable filter and at least one pair of photo detectors. The detectors have photo sensitive regions with their areas varying with the position in one direction. The wavelength for maximum transmission of the variable filter varies in the same direction. By comparing the photo current values from the two detectors, wavelength of the incident beam is determined. Methods to construct wavelength discrimination junction photo detector pair and double barrier photo detector pair are also given.

Abstract: The present invention describes a method to detect leaks in a roof or leaks in basement walls or floors of a building. The detection is achieved by placing a two wire detector in the region to be monitored and measuring the current with a voltage applied across the two wires. The location of the leak is determined by placing several wire detector pairs in a mesh fashion and then scanning the leakage current through each wire pair. A complete detection and scanning system is also described.