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Each of these technologies has been prototyped and tested and is nearly ready for transfer to commercial applications.
Microdischarge Lamp
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U.S. Patent #6,016,027
U.S. Patent #6,139,384
The microdischarge lamp has a hollow cathode geometry with the cathode formed in a one-piece substrate, such as a silicon wafer. Integrated circuit micromachining and fabrication techniques are used to form microcavities in the substrate. The substrate consists of a conductive layer, topped by a dielectric, topped by another conductive layer. The microcavity is filled with a gas. When a voltage is applied across the layers, a discharge occurs and light is emitted. This technology is 100% owned by the University.
Benefits
- Inexpensive: The method uses well-entrenched integrated circuit micromachining and fabrication techniques to form the microcavities inexpensively. Also, this lamp can be fabricated in one substrate, unlike in previous methods.
- Efficient: The small dimensions that are possible with this design permit the efficient production of light from new radiators.
- Easier to mass produce: The mass production techniques used to produce these lamps are readily available.
- High gas pressures: The dimensions of the discharge lamp can be made so small that the gas pressure can be raised well above what is possible with a conventional discharge lamp, while still producing wavelengths that are not possible from other lamps.
Publications
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- "Microdischarge Devices Fabricated in Silicon," published Sept. 1, 1997, in Applied Physics Letters 71(9):1165–1167.
- "Planar Microdischarge Arrays," published July 23, 1998, in Electronics Letters 34(15): 1529–1531.
- "Continuous-Wave Emission in the Ultraviolet from Diatomic Excimers in a Microdischarge," published May 25, 1998, in Applied Physics Letters 72(21):2634–2636.
- "Microdischarge Arrays: A New Family of Photonic Devices," published Jan./Feb. 2002 in IEEE Journal on Selected Topics in Quantum Electronics 8(1):139–147.
- "Arrays of Silicon Microdischarge Devices with Multicomponent Dielectrics," published Nov. 15, 2001, in Optics Letters 26(22):1773–1775.
- "Performance of Microdischarge Devices and Arrays with Screen Electrodes," published Jan. 2001 in IEEE Photonics Technology Letters 13(1):61-63.
Microdischarge Lamp and Array
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U.S. Patent #6,194,833
This multilayer microdischarge device has three components: (1) a silicon substrate acting as a planar electrode, (2) a dielectric layer deposited onto the silicon substrate, and (3) a top conducting film. Cavities are machined into the conducting and dielectric layers to expose the silicon; these cavities then are filled with gas or vapor. When a voltage is applied between the silicon and conducting film, a plasma is formed inside the cavity. This technology is 100% owned by the University.
Benefits
- Easily produced in arrays: Because both electrodes are planar, manufacturing is greatly simplified, and the microdischarge devices can be easily produced in arrays.
- Simply manufactured: Microdischarge devices take advantage of well-established silicon processing methods and are thus easily fabricated.
- Versatility of use: The devices work well not only with gases but also with low vapor pressure materials that require heating.
Publications
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- "Planar Microdischarge Arrays," published July 23, 1998, in Electronics Letters 34(15): 1529–1531.
- "Arrays of Silicon Microdischarge Devices with Multicomponent Dielectrics," published Nov. 15, 2001, in Optics Letters 26(22):1773–1775.
- "Independently Addressable Subarrays of Silicon Microdischarge Devices: Electrical Characteristics of Large (30x30) Arrays and Excitation of a Phosphor," published Sept. 24, 2001, in Applied Physics Letters 79(13):2100–2102.
- "Arrays of Microdischarge Devices Having 50–100 µm Square Pyramidal Si Anodes and Screen Cathodes," published Feb. 1, 2001, in Electronics Letters 37(3):171-172.
- "Silicon Microdischarge Devices Having Inverted Pyramidal Cathodes: Fabrication and Performance of Arrays," published Jan. 22, 2001, in Applied Physics Letters 78(4):419–421.
- "Performance of Microdischarge Devices and Arrays with Screen Electrodes," published Jan. 2001 in IEEE Photonics Technology Letters 13(1):61-63.
Flexible Microdischarge Device/Array
This technology is used to produce flexible microdischarge devices and arrays inexpensively. Inexpensive materials, such as copper coil, are used as the cathode as well as for flexible support for the device. A thin film of polyimide serves as the dielectric, and a thin metallic film acts as the anode. A channel is machined through these three layers and is filled with a suitable gas. When a voltage is applied across the layers, a discharge is produced. This technology is 100% owned by the University.
Benefits
- Reduced cost: Use of less expensive materials and novel design reduce the production cost.
- Mass production possible: The small overall thickness of the layers allows for manufacturing of these devices to be accomplished in large sheets using "roll-to-roll" manufacturing.
Publications
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Multilayer Ceramic Microdischarge Device
This device is fabricated using multilayer ceramic integrated circuit (MCIC) technology to form the cavity and electrode structure. Essentially, an MCIC capacitor structure is fabricated, and then a hole is drilled into the structure. The resulting device has a through-hole and can be used with interdigitated electrodes. This technology is 100% owned by the University.
Benefits
- Resistance to harsh environments: The ceramic materials of the device make it suitable for use at high temperatures and in harsh chemical environments, making it ideal for use in the remediation of toxic gases.
- Small size: Since the device can be easily integrated with other components, such as MCIC inductors and capacitors as well as with hybrid packaged silicon integrated circuits, it can be much smaller in size.
Publications
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- "Multistage, Monolithic Ceramic Microdischarge Device Having an Active Length of ~0.27 mm," published March 5, 2001, in Applied Physics Letters 78(10):1340–1342
- "Performance of Microdischarge Devices and Arrays with Screen Electrodes," published Jan. 2001 in IEEE Photonics Technology Letters 13(1):61-63.
All-Silicon Microdischarge
This technology is a means of exciting a microdischarge using a reverse-biased pn junction or Schottky diode, where the entire device is made from one silicon wafer. In this configuration, the depletion region behaves like the dielectric layer in the other configurations, resulting in a more simply fabricated and robust microdischarge device. Since the width of the depletion region depends on the magnitude of the voltage bias, the device behaves as if it has a variable thickness dielectric that can be controlled at will. This technology is 100% owned by the University.
Benefits
- Simple fabrication: Since the entire device is made from one material, it is fabricated simply. Also, the cavity is more easily drilled through one material rather than three
- Robust device: With silicon as the material—and since silicon is virtually impervious to sputtering—the overall device is more robust.
- Variable dielectric: Since the width of the depletion region depends on the magnitude of the voltage bias, the device behaves as if it has a variable thickness dielectric that can be controlled at will.
- Ability to function at radio frequencies: Adjusting the voltage bias brings the device into resonance with the frequency of the driver, allowing it to be run at radio frequencies (RF). RF discharges are desirable because they are efficient, have long lifetimes, and provide low-cost sources of light for use in low-cost communication systems.
Publications
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Starting and Reigniting Arc Lamps
This technology is a method for more easily igniting and reigniting high-pressure arc lamps. It adds microdischarge devices to produce and inject electrons to augment electron production in the early stages of lamp ignition or reignition so that less voltage and time are required to ignite the lamp. This technology is jointly owned by the University and APL Engineered Materials, Inc.
Benefits
- Easier and faster ignition: The discharge augments electron production in the ignition system of the lamp so that less voltage (by at least a factor of 2) and less time are required to ignite the lamp than without starting aids.
- Extended lifetime: Each time a lamp is ignited, it loses 10 hours of its overall lifetime due to the extremely high voltage peak required for ignition. Decreasing that voltage significantly could increase the lamp’s useful lifetime.
Publications
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- "Reduction in the Breakdown Voltage of a High Pressure Discharge with an Array of 200-400 µm Diameter Microdischarges: Application to Arc Lamp Ignition," published Feb. 2002 in IEEE Transactions on Plasma Science 30(1, part 1):194–195.
- "Microdischarge Array-Assisted Ignition of a High-Pressure Discharge: Application to Arc Lamps," published Dec. 24, 2001, in Applied Physics Letters 79(26):4304–4306.
- "Performance of Microdischarge Devices and Arrays with Screen Electrodes," published Jan. 2001 in IEEE Photonics Technology Letters 13(1):61-63.
Thin, Lightweight Microdischarge Devices/Arrays
This microdischarge device is formed from a semiconductor electrode with a cavity, an insulating layer, and a second electrode. The cavity in the silicon is a square-pyramid shape, and shape would vary depending on the semiconductor used. Multiple devices may be fabricated in one silicon wafer to produce an array. This invention can be used with any of the other inventions that make use of semiconductor systems.
Benefits
- Inexpensive: Tapered cavities are relatively inexpensive and easy to fabricate using conventional semiconductor processing techniques.
- Superior performance: The resulting devices have superior electrical and optical characteristics and lifetimes compared to those of conventional microdischarge devices. Arrays of the devices produce considerable output power and exhibit ignition characteristics superior to those of conventional arrays of devices.
- Enabling: The large positive differential resistance of devices with tapered arrays decreases power consumption, while the linearity of the V-I characteristics permits self-ballasting of the devices and simplifies external control circuitry.
- More efficient: Sides of cavity can be coated with a thin film of material to reflect light in the spectral region of interest and improve the efficiency for extracting light from a microdischarge device.
Publications
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- "Silicon Microdischarge Devices Having Inverted Pyramidal Cathodes: Fabrication and Performance of Arrays," published Jan. 22, 2001, in Applied Physics Letters 78(4):419–421.
- "Arrays of Microdischarge Devices Having 50–100 µm Square Pyramidal Si Anodes and Screen Cathodes," published Feb. 1, 2001, in Electronics Letters 37(3):171-172.
- "Independently Addressable Subarrays of Silicon Microdischarge Devices: Electrical Characteristics of Large (30x30) Arrays and Excitation of a Phosphor," published Sept. 24, 2001, in Applied Physics Letters 79(13):2100–2102.
- "Arrays of Silicon Microdischarge Devices with Multicomponent Dielectrics," published Nov. 15, 2001, in Optics Letters 26(22):1773–1775.
- "Microdischarge Arrays: A New Family of Photonic Devices," published Jan./Feb. 2002 in IEEE Journal on Selected Topics in Quantum Electronics 8(1):139–147.
- "Performance of Microdischarge Devices and Arrays with Screen Electrodes," published Jan. 2001 in IEEE Photonics Technology Letters 13(1):61-63.
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