Abstract: The present invention provides the multifunctional biological and biochemical sensor technology based on ZnO nanostructures. The ZnO nanotips serve as strong DNA or protein molecule binding sites to enhance the immobilization. Patterned ZnO nanotips are used to provide conductivity-based biosensors. Patterned ZnO nanotips are also used as the gate for field-effect transistor (FET) type sensors. Patterned ZnO nanotips are integrated with SAW or BAW based biosensors. These ZnO nanotip based devices operate in multimodal operation combining electrical, acoustic and optical sensing mechanisms. The multifunctional biosensors can be arrayed and combined into one biochip, which will enhance the sensitivity and accuracy of biological and biochemical detection due to strong immobilization and multimodal operation capability. Such biological and biochemical sensor technology are useful in detection of RNA-DNA, DNA-DNA, protein-protein, protein-DNA and protein-small molecules interaction.

Abstract: In the present invention, there are provided self-assembled ZnO nanotips grown on relatively low temperatures on various substrates by metalorganic chemical vapor deposition (MOCVD). The ZnO nanotips are made at relatively low temperatures, giving ZnO a unique advantage over other wide bandgap semiconductors such as GaN and SiC. The nanotips have controlled uniform size, distribution and orientation. These ZnO nanotips are of single crystal quality, show n-type conductivity and have good optical properties. Selective growth of ZnO nanotips also has been realized on patterned (100) silicon on r-sapphire (SOS), and amorphous SiO2 on r-sapphire substrates. Self-assembled ZnO nanotips can also be selectively grown on patterned layers or islands made of a semiconductor, an insulator or a metal deposited on R-plane (01{overscore (1)}2) Al2O3 substrates as long as the ZnO grows in a columnar stucture along the c-axis [0001] of ZnO on these materials.

Abstract: A method and apparatus for creating and detecting an optically encoded document having a uniquely designed document verification indicator is disclosed. One embodiment includes applying a spatially varying Brewster angle pattern on a substrate. Another embodiment includes an apparatus for detecting the spatially varying Brewster angle pattern including a light source, a slit aperture, a polarizer, at least one parabolic mirror, and an image capturing device.

Abstract: In the present invention, there is provided semiconductor devices such as a Schottky UV photodetector fabricated on n-type ZnO and MgxZn1-xO epitaxial films. The ZnO and MgxZn1-xO films are grown on R-plane sapphire substrates and the Schottky diodes are fabricated on the ZnO and MgxZn1-xO films using silver and aluminum as Schottky and ohmic contact metals, respectively. The Schottky diodes have circular patterns, where the inner circle is the Schottky contact, and the outside ring is the ohmic contact. Ag Schottky contact patterns are fabricated using standard liftoff techniques, while the Al ohmic contact patterns are formed using wet chemical etching. These detectors show low frequency photoresponsivity, high speed photoresponse, lower leakage current and low noise performance as compared to their photoconductive counterparts. This invention is also applicable to optical modulators, Metal Semiconductor Field Effect Transistors (MESFETs) and more.

Abstract: The present invention provides the multifunctional biological and biochemical sensor technology based on ZnO nanostructures. The ZnO nanotips serve as strong DNA or protein molecule binding sites to enhance the immobilization. Patterned ZnO nanotips are used to provide conductivity-based biosensors. Patterned ZnO nanotips are also used as the gate for field-effect transistor (FET) type sensors. Patterned ZnO nanotips are integrated with SAW or BAW based biosensors. These ZnO nanotip based devices operate in multimodal operation combining electrical, acoustic and optical sensing mechanisms. The multifunctional biosensors can be arrayed and combined into one biochip, which will enhance the sensitivity and accuracy of biological and biochemical detection due to strong immobilization and multimodal operation capability. Such biological and biochemical sensor technology are useful in detection of RNA-DNA, DNA-DNA, protein-protein, protein-DNA and protein-small molecules interaction.

Abstract: The present invention provides the multifunctional biological and biochemical sensor technology based on ZnO nanostructures. The ZnO nanotips serve as strong DNA or protein molecule binding sites to enhance the immobilization. Patterned ZnO nanotips are used to provide conductivity-based biosensors. Patterned ZnO nanotips are also used as the gate for field-effect transistor (FET) type sensors. Patterned ZnO nanotips are integrated with SAW or BAW based biosensors. These ZnO nanotip based devices operate in multimodal operation combining electrical, acoustic and optical sensing mechanisms. The multifunctional biosensors can be arrayed and combined into one biochip, which will enhance the sensitivity and accuracy of biological and biochemical detection due to strong immobilization and multimodal operation capability. Such biological and biochemical sensor technology are useful in detection of RNA-DNA, DNA-DNA, protein-protein, protein-DNA and protein-small molecules interaction.

Abstract: In the present invention, there is provided semiconductor devices such as a Schottky UV photodetector fabricated on n-type ZnO and MgxZn1-xO epitaxial films. The ZnO and MgxZn1-xO films are grown on R-plane sapphire substrates and the Schottky diodes are fabricated on the ZnO and MgxZn1-xO films using silver and aluminum as Schottky and ohmic contact metals, respectively. The Schottky diodes have circular patterns, where the inner circle is the Schottky contact, and the outside ring is the ohmic contact. Ag Schottky contact patterns are fabricated using standard liftoff techniques, while the Al ohmic contact patterns are formed using wet chemical etching. These detectors show low frequency photoresponsivity, high speed photoresponse, lower leakage current and low noise performance as compared to their photoconductive counterparts. This invention is also applicable to optical modulators, Metal Semiconductor Field Effect Transistors (MESFETs) and more.

Abstract: The present invention provides magnesium zinc oxide (MgxZn1-xO) as a new piezoelectric material, which is formed by alloying ZnO and MgO. MgxZn1-xO allows for flexibility in thin film SAW and BAW device design, as its piezoelectric properties can be tailored by controlling the Mg content, as well as by using MgxZn1-xO/ZnO multilayer structures. To experimentally prove it, the MgxZn1-xO (x≦0.35) thin films are grown on r-plane sapphire substrates at a temperature in the range of 400° C.-500° C. by metalorganic chemical vapor deposition. MgxZn1-xO films with Mg mole percent up to 0.35 have epitaxial quality and wurtzite crystal structure. The SAW properties, including velocity dispersion and piezoelectric coupling, are characterized and concluded that the acoustic velocity increases, whereas the piezoelectric coupling decreases with increasing Mg mole percent in piezoelectric MgxZn1-xO films.

Abstract: The present invention provides a ZnO based tunable surface acoustic wave (SAW), preferably monolithically integrated tunable SAW (MITSAW) device. The MITSAW comprises a ZnO/MgxZn1−xO quantum well structure and piezoelectric ZnO thin film epitaxially grown on R-plane sapphire ((01{overscore (1)}2)Al2O3) substrate using MOCVD. R-plane sapphire provides in-plane anisotropy in the ZnO layer as the c-axis of ZnO lies in the growth plane. A two-dimensional electron gas (2DEG) is placed in the delay path of the SAW device and interacts with the lateral electric field resulting in ohmic loss which attenuates and slows the surface acoustic wave. This mechanism is used to tune the acoustic velocity. The high coupling coefficients offered by the ZnO/R-(Al2O3) system allows large velocity tuning. ZnO based MITSAW is used for chemical and biochemical sensors, offers excellent manufacturability, high yield and low cost. Such SAW sensors have a “resettable” sensing mechanism.

Abstract: In the present invention, there are provided self-assembled ZnO nanotips grown on relatively low temperatures on various substrates by metalorganic chemical vapor deposition (MOCVD). The ZnO nanotips are made at relatively low temperatures, giving ZnO a unique advantage over other wide bandgap semiconductors such as GaN and SiC. The nanotips have controlled uniform size, distribution and orientation. These ZnO nanotips are of single crystal quality, show n-type conductivity and have good optical properties. Selective growth of ZnO nanotips also has been realized on patterned (100) silicon on r-sapphire (SOS), and amorphous SiO2 on r-sapphire substrates. Self-assembled ZnO nanotips can also be selectively grown on patterned layers or islands made of a semiconductor, an insulator or a metal deposited on R-plane (01{overscore (1)}2) Al2O3 substrates as long as the ZnO grows in a columnar stucture along the c-axis [0001] of ZnO on these materials.

Abstract: The present invention provides a ZnO based tunable surface acoustic wave (SAW), preferably monolithically integrated tunable SAW (MITSAW) device. The MITSAW comprises a ZnO/MgxZn1−xO quantum well structure and piezoelectric ZnO thin film epitaxially grown on R-plane sapphire ((01{overscore (1)}2)Al2O3) substrate using MOCVD. R-plane sapphire provides in-plane anisotropy in the ZnO layer as the c-axis of ZnO lies in the growth plane. A two-dimensional electron gas (2DEG) is placed in the delay path of the SAW device and interacts with the lateral electric field resulting in ohmic loss which attenuates and slows the surface acoustic wave. This mechanism is used to tune the acoustic velocity. The high coupling coefficients offered by the ZnO/R-(Al2O3) system allows large velocity tuning. ZnO based MITSAW is used for chemical and biochemical sensors, offers excellent manufacturability, high yield and low cost. Such SAW sensors have a “resettable” sensing mechanism.

Abstract: The present invention provides a ZnO based tunable surface acoustic wave (SAW), preferably monolithically integrated tunable SAW (MITSAW) device. The MITSAW comprises a ZnO/Mgx Zn1−xO quantum well structure and piezoelectric ZnO thin film epitaxially grown on R-plane sapphire ((01{overscore (1)}2)Al2O3) substrate using MOCVD. R-plane sapphire provides in-plane anisotropy in the ZnO layer as the c-axis of ZnO lies in the growth plane. A two-dimensional electron gas (2DEG) is placed in the delay path of the SAW device and interacts with the lateral electric field resulting in ohmic loss which attenuates and slows the surface acoustic wave. This mechanism is used to tune the acoustic velocity. The high coupling coefficients offered by the ZnO/R-(Al2O3) system allows large velocity tuning. ZnO based MITSAW is used for chemical and biochemical sensors, offers excellent manufacturability, high yield and low cost. Such SAW sensors have a “resettable” sensing mechanism.

Abstract: In the present invention, there is provided semiconductor devices such as a Schottky UV photodetector fabricated on n-type ZnO and MgxZn1-xO epitaxial films. The ZnO and MgxZn1-xO films are grown on R-plane sapphire substrates and the Schottky diodes are fabricated on the ZnO and MgxZn1-xO films using silver and aluminum as Schottky and ohmic contact metals, respectively. The Schottky diodes have circular patterns, where the inner circle is the Schottky contact, and the outside ring is the ohmic contact. Ag Schottky contact patterns are fabricated using standard liftoff techniques, while the Al ohmic contact patterns are formed using wet chemical etching. These detectors show low frequency photoresponsivity, high speed photoresponse, lower leakage current and low noise performance as compared to their photoconductive counterparts. This invention is also applicable to optical modulators, Metal Semiconductor Field Effect Transistors (MESFETs) and more.

Abstract: The present invention provides magnesium zinc oxide (MgxZn1-xO) as a new piezoelectric material, which is formed by alloying ZnO and MgO. MgxZn1-xO allows for flexibility in thin film SAW and BAW device design, as its piezoelectric properties can be tailored by controlling the Mg content, as well as by using MgxZn1-xO/ZnO multilayer structures. To experimentally prove it, the MgxZn1-xO (x≦0.35) thin films are grown on r-plane sapphire substrates at a temperature in the range of 400° C.-500° C. by metalorganic chemical vapor deposition. MgxZn1-xO films with Mg mole percent up to 0.35 have epitaxial quality and wurtzite crystal structure. The SAW properties, including velocity dispersion and piezoelectric coupling, are characterized and concluded that the acoustic velocity increases, whereas the piezoelectric coupling decreases with increasing Mg mole percent in piezoelectric MgxZn1-xO films.

Abstract: A ZnO monolithically integrated tunable surface acoustic wave (MITSAW) device uses tunable acousto-electric and acouso-optic interaction between surface acoustic waves (SAW) and a two dimensional electron gas (2DEG) in a ZnO/MgxZn1−xO quantum well. The high electromechanical coupling coefficients of piezoelectric ZnO in conjunction with the low acoustic loss and high velocity of sapphire (Al2O3) offers high frequency and low loss RF applications. The 2DEG interacts with the lateral electric field resulting in ohmic loss which attenuates and slows the surface acoustic wave. This mechanism is used to tune the acoustic velocity. The high coupling coefficients offered by the ZnO/R—(Al2O3) systems allows large velocity tuning. Combined with the optical characteristics of the wide and direct band gap (about 3.3 eV) semiconductor and transparent ZnO electrodes, the MITSAW chip can be used for UV optical signal processing.

Abstract: A novel programmable SAW filter with switchable multi-element interdigital transducers (IDTs) controlled by a microprocessor or a computer is provided that realizes the tunability of both center frequency and bandwidth of the SAW filter. The filter possesses the feature of the programmability of both center frequency and 3 dB bandwidth. As an example design, the center frequency of the SAW filter ranges from 126.8 MHz to 199.1 MHz while the 3 dB bandwidth ranges from 18.8 MHz to 58.9 MHz. The multi-input configuration increases the programmability of the device and improves insertion loss. A matching network for the programmable SAW filter further improves insertion loss level and stopband attenuation. A resistance weighting method has been applied to improve in band ripple with the passband ripple being reduced from 6.44 dB to 1.37 dB after resistance weighting.

Abstract: A novel programmable SAW filter with switchable multi-element interdigital transducers (IDTs) controlled by a microprocessor or a computer is provided that realizes the tunability of both center frequency and bandwidth of the SAW filter. The filter possesses the feature of the programmability of both center frequency and 3 dB bandwidth. As an example design, the center frequency of the SAW filter ranges from 126.8 MHz to 199.1 MHz while the 3 dB bandwidth ranges from 18.8 MHz to 58.9 MHz. The multi-input configuration increases the programmability of the device and improves insertion loss. A matching network for the programmable SAW filter further improves insertion loss level and stopband attenuation. A resistance weighting method has been applied to improve in band ripple with the passband ripple being reduced from 6.44 dB to 1.37 dB after resistance weighting.

Abstract: MITSAW devices use tunable acousto-electric and acousto-optic interaction between surface acoustic waves (SAW) and a two dimensional electron gas (2DEG) in a ZnO/MgxZn1−xO quantum well to tune acoustic velocity in the SAW delay line. The MITSAW comprises a ZnO/MgxZn1−xO quantum well structure and piezoelectric ZnO thin films grown on R-plane sapphire (Al2O3) substrate using MOCVD. R-plane sapphire provides in-plane anisotropy in the ZnO layer. The 2DEG is placed in the delay path of the SAW device and interacts with the lateral electric field resulting in ohmic loss which attenuates and slows the surface acoustic wave. This mechanism is used to tune the acoustic velocity. The high coupling coefficients offered by the ZnO/R—(Al2O3) systems allows large velocity tuning. ZnO based MITSAW is used for chemical and biochemical sensors, offers excellent manufacturability, high yield and low cost. Such SAW sensors have a “resettable” sensing mechanism.

Abstract: A ZnO monolithically integrated tunable surface acoustic wave (MITSAW) device uses tunable acousto-electric and acouso-optic interaction between surface acoustic waves (SAW) and a two dimensional electron gas (2DEG) in a ZnO/MgxZn1-xO quantum well. The high electromechanical coupling coefficients of piezoelectric ZnO in conjunction with the low acoustic loss and high velocity of sapphire (Al2O3) offers high frequency and low loss RF applications. The 2DEG interacts with the lateral electric field resulting in ohmic loss which attenuates and slows the surface acoustic wave. This mechanism is used to tune the acoustic velocity. The high coupling coefficients offered by the ZnO/R-(Al2O3) systems allows large velocity tuning. Combined with the optical characteristics of the wide and direct band gap (about 3.3 eV) semiconductor and transparent ZnO electrodes, the MITSAW chip can be used for UV optical signal processing.

Abstract: A high contrast ultrahigh speed optically-addressed ultraviolet light modulator exploits the optical anisotropy in a ZnO film epitaxially grown on (01 {overscore (1)}2) sapphire. This device, which could also be realized in a ZnO bulk crystal or similar wide bandgap material, achieves both high contrast and high speed by exploiting the anisotropic bleaching of the anisotropic absorption and concomitant ultrafast polarization rotation near the lowest exciton resonances produced by femtosecond ultraviolet pulses. The resultant modulation in a preferred embodiment is characterized by a contrast ratio of 70:1, corresponding to a dynamic polarization rotation of 12°, and decays to a quasi-equilibrium value within 100 ps.