Category Archives: Electronics & Optronics

Semiconductors, fiber optics, antenna systems, spintronics, etc.

Direct, Low Frequency Capacitance Measurement for Scanning Capacitance Microscopy

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Summary:

Scanning capacitance microscopy (SCM) circuits, used for such applications as semiconductor characterization (including dopant profiling, device characterization, and surface defect characterization), are typically not adapted for calibrated, low frequency measurements of absolute capacitance. In fact, these implementations of SCM generally do not measure capacitance directly. Rather, they measure the change in capacitance versus the change in voltage (dC/dV) by varying the probe-sample voltage V at frequencies greater than 10 kHz. This is due to a voltage dependant capacitance resulting from a voltage-dependant space change layer in the semiconductor substrate. The Ohio State University has developed a system and method for performing scanning capacitance microscopy using an atomic force microscope (AFM) that measures direct capacitance at a frequency less then 10 kHz. The system exhibits high sensitivity with very low noise. Recent advancements to this technology have resulted in even higher sensitivity by enabling direct measurements of absolute capacitance at higher frequencies. The design of the circuit has also been simplified, enabling the use of off-the-shelf components such as function generators. This straightforward design will shorten the investment of time and money needed to commercialize this powerful system.

Potential Applications:

This system is an ideal tool for semiconductor characterization. It is also useful for measuring a wide variety of dielectric films such as SiO2 grown on Si, or for dielectric films on other semiconductor substrates such as Si3N4, Al2O3, TiO2, and ZrO2. It may also be used to measure thin lubricant films such as perfluoropolyethers, a widely used class of compounds for MEMS and hard disk drive lubrication. Other suitable types of samples include self-assembled monolayers.

Advantages:

  • Enables direct capacitance measurements at low frequencies
  • Low noise
  • High sensitivity
  • Straightforward yet powerful design
  • Can also determine stray capacitance

Dual band cellular/GPS semicircular loop slot in metal film

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Summary:

Researchers at the Ohio State University have developed a unique conformal slot antenna that can be used in a cellular or GPS application. This antenna is designed to transmit and/or receive radio signals in more than one frequency band. Prototypes of this design show that we can obtain GPS (Global Positioning Satellite) performance equal to the best commercial antenna tested so far.

Potential Applications:

For use in cellular or GPS devices.

Advantages:

Performance that is equal to or better than the best commercial antenna tested to date.

Resonant Interband Tunneling Diodes–Extending Moore’s Law and Enabling New Circuitry

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Summary:

Since the early 1960’s, the utility of the tunnel diode (or Esaki diode) has been evident, but several practical hurdles have kept it from reaching mainstream status. Historically, it has been difficult to control peak current and, more importantly, tunnel diode fabrication has lacked a Si-based process that can easily be mass produced and integrated into existing Si-based integrated circuits. As a result, today’s tunnel diodes are primarily used in discrete form and for niche applications. Regardless, tunnel diodes have many current and future applications, and the challenges of aggressively scaled CMOS is forcing this subject to be seriously revisited, since quantum tunneling will dominate in any ultra-low dimensional material. The structure of the Resonant Interband Tunneling Diode (RITD) differs from that of the Esaki diode (traditional tunnel diode) which results in additional useful properties. In RITDs, electrons quantum mechanically tunnel across an energy well formed between two barriers, where Esaki diodes have no energy well. This quantum mechanical tunneling effect happens extremely quickly and thus very high speed electronics can be realized with the use of RITDs. Terahertz operation has been demonstrated. Furthermore, a useful effect called Negative Differential Resistance (NDR) can be exploited using these devices.

Potential Applications:

  • Can augment CMOS technology resulting in novel logic and embedded circuit topologies with reduced device count, low power, and faster speed.
  • Can be implemented in ICs, memory devices, and small, lightweight portable electronics for greater performance at lower power consumption
  • Applications found in oscillators, frequency locking circuits, advanced SRAM circuits, highly integrated A/D converters, high speed digital latches, and many others

Advantages:

  • Uses quantum tunneling, a very high-speed process. Terahertz operation has been demonstrated
  • Shown to exhibit Negative Differential Resistance (NDR)
  • Low cost, compatible with current CMOS technology, and easy to integrate into existing manufacturing processes
  • Runs at room temperature and at very low voltage
  • Can be combined with existing technologies to offer flexibility

IP Status:

Tunneling Diode: Use and Manufacturing – US Pending
Using Backward Tunneling Diode as a Sensor – US Pending

Two-Layered Micro Channel Heat Sink Concept in Electronic Cooling

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Summary:

Heat removal has become an important factor in the advancement of microelectronics due to drastically integrated density of chips in digital devices and increased current-voltage handling capability of power electronic devices. Micro-channel heat sinks remove heat 50 times more efficiently than conventional methods. However, one-layered micro-channel heat sinks induce high temperatures which can produce thermal stress on the chips and packages. To avoid such high temperatures, a large pressure drop is necessary which moves the coolant through the cooling channels more rapidly, thus requiring a larger, noisier pumping system. Scientists at The Ohio State University have developed a multi-layered micro-channel heat sink with a current flow arrangement for cooling that is a substantial improvement over conventional one-layered micro-channel heat sink designs. The thermal performance and the temperature distribution for these types of micro-channels were analyzed and a procedure for optimizing the geometrical design parameters was developed. While the power supply system of the multi-layered design is not significantly more complicated than the one-layered design, the stream-wise temperature rise on the base of surface was substantially reduced. At the same time, the pressure drop required for the multi-layered heat sink was substantially smaller than the one-layer design. It is shown that the thermal resistance is as low as 0.03 ?C/W for micro-channel heat sinks, which is substantially lower than conventional channel-sized heat sinks.

Potential Applications:

The multi-layered micro-channel design is ideal for the electronics semiconductor industry. More efficient cooling of solid-state radar systems, diode lasers, and mainframe and supercomputers are just a few of the applications. Using this technology for laser cooling is simpler than for microelectronics cooling. Research has demonstrated that the method works quite well for surfaces with a diameter of roughly up to 10 cm.

Advantages:

  1. Cools far more efficiently than conventional cooling methods
  2. Cools surfaces as well as single-layer micro-channels but holds two noticeable improvements in efficiency:
    1. Stream-wise temperature rise on the base of surface is substantially reduced compared to single-layer micro-channels.
    2. Pressure drop required for the multi-layered heat sink is substantially smaller than the single-layer design.
    3. Size of coolant pumping system is reduced.

Organic based spintronic devices

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Summary:

Researchers at the Ohio State University have discovered a novel organic based spintronic device. Organic based spintronic devices in which the electron spin degree of freedom controls the electric current enhances a broad range of technologies, most notably mass storage. The use of spintronics have played a key role in the dramatic increase of areal density found in mass storage devices, enabling the storage of massive amounts of data on a small platter.

Organic based spintronic devices have enhanced functionality, are easy to manufacture, and are less expensive to manufacture than inorganic ones.

Potential Applications:

Mass-storage devices

Advantages:

  • Enhanced functionality
  • Ease of manufacturing
  • Lower cost

Implementation of Light-Free Capacitive Displacement Detection for Magnetic Resonance Force Microscopy

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Summary:

Magnetic resonance signal is detected via displacement detection of a micromechanical cantilever. Usually, this is done by means of fiber-optical laser interferometry. However, in many systems, laser light disrupts magnetic resonance signal. At The Ohio State University, we are the first to implement MRFM with light-free capacitive displacement readout that can perform subsurface imaging on a nanometer scale.

Potential Applications:

  • Solid state quantum computer
  • Semiconducting devices
  • It can detect a range of magnetic resonance phenomena (EPR, NMR, FMR) making it applicable to various physical systems

Advantages:

  • The depth of probing can measure to the nanometer scale to image molecules.
  • Improved sensitivity could exceed optical techniques
  • Capacitive detection will eventually replace optical detection
  • There is no laser light to disrupt the magnetic resonance signal
  • Displacement detection is integrated into the device allowing it to be fabricated at the same time making it enabling for parallelization

Undetectable, Unjammable, and Interference-Free Ultra Wideband Radar System

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Summary:

Researchers at the Ohio State University have developed a virtually undetectable ultra wide band radar system that transmits pseudo random noise. On receive, the radar system cross-correlates a copy (possibly modified) of the original waveform with the receive signals. If a target reflects the signal (with modifications) then the radar will detect the reflection, the time delay, and Doppler. Thus the radar can tell the distance to a reflecting object and its relative speed. This is done using a waveform that will not interfere with other users of the spectrum. The noise waveform is extremely hard to detect. Researchers have further developed a system of storing the waveforms and performing the cross correlation at a particular time delay using a single memory device and no delay devices. This lends to the creation of a small, low cost, low power, stealthy radar that cannot be easily detected by conventional radar detection equipment and can be used for very short range applications. The radar can also be used to identify radar targets by using a pair of waveforms matched to the target radar impulse response. Thus the radar can also be used to detect only specific types of targets, as maybe required by the application.

Potential Applications:

  • Speed radar gun manufacturers seeking an undetectable radar gun
  • Simple moving vehicle/person/object with identification potential (automotive lane change warning)
  • Highway management to evaluate strength of material, or helicopter air to air warning systems
  • Low cost ground penetration radar for pipes, land mine detection, or probing human bodies
  • Low cost building penetration radar (security systems at casinos and airports)
  • Cross section instrumentation radar with inverse synthetic aperture imaging radar ability
  • Moving Radar, synthetic aperture radar systems

Advantages:

  • Robust with reference to interference or jamming – thus undetectable and hard to intercept
  • Unlikely to interfere with other noise radar systems or other radar systems in the same band
  • Low cost, small, light weight, and can be used for very short-range applications
  • Can be trained to be target specific (with the ability to specify multiple targets)
  • Would require no license to operate in civilian bands, and is fully coherent in amplitude and phase

Printed circuit emulation of anisotropic media for generating slow waves and field amplification in microwave and antenna components

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Summary:

For the first time ever, researchers at the Ohio State University have been able to use simple microwave circuit components to emulate the extraordinary propagation phenomena traditionally encountered in periodic assemblies of bulk anisotropic dielectric and gryomagnetic ferrite materials. The researchers have been able to realize degenerate band edge resonances as well as frozen modes using uniquely invented, cost effective, and easy to manufacture microstrip transmission lines arrangements (Printed Circuit technology). The field growth and amplification effects of these remarkable modes allows for miniaturization of microwave and optical circuit components such as coupled lines, delay elements, printed antennas, and antenna arrays. These microwave circuits can also be coupled with mature circuit optimization tools to quickly design metamaterials displaying the same electromagnetic modes. The proposed microwave circuits can be further extended to solid state semiconductor optoelectronics devices via standard IC manufacturing technology.

Potential Applications:

  • Miniaturization of microwave and optical circuit components such as coupled lines, delay elements, phase shifters, printed antennas, antenna arrays, and solid state semiconductor optoelectronic devices
  • Efficient metamaterial design
  • Frequency mixing and modulation applications

Advantages:

  • Compared to metamaterials, realizing the same modes is much easier and significantly less expensive
  • Easy to manufacture in volume production since it is based on printed circuit technology
  • Easy retrofit with existing manufacturing processes
  • Very cost effective

A High-Efficiency Chemical Looping Process to Produce Low-Cost Hydrogen from Gaseous Fuels

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Summary:

Researchers at The Ohio State University have developed a highly efficient chemical looping process that utilizes cyclic redox reactions of metal oxide (MO) particles with gaseous fuels (like syngas and natural gas) and steam to produce hydrogen. Named as SynGas Redox (SGR), the process as developed is a marked improvement over the conventional Steam-Iron process to produce hydrogen.

MO + CO/H2/CH4 <-> M + CO2 + H2O
M + H2O <-> MO + H2

The primary metal oxide in SGR is Fe2O3 which is converted to Fe on reaction with syngas. The reactor design allows for a complete conversion of syngas to a mixture of carbon dioxide and water, exiting the reactor using the same high pressure of the gasifier. Upon condensation of water, a relatively pure stream of carbon dioxide is produced which is ready for sequestration. The iron oxide is regenerated in a second reactor, the design of which is also optimized for maximum conversion of steam to hydrogen.

The process has been demonstrated on a bench scale reactor with significant success, including detailed ASPEN simulations. The process has also been optimized (and integrated) for syngas derived from a commercially available dry feed bituminous coal gasifier. Close to 75% of the coal HHV (high heating value) can be converted to hydrogen HHV, suggesting a much higher efficiency than the conventional coal gasification-water gas shift route to hydrogen. Preliminary cost analysis suggests a significant reduction in the cost of hydrogen as compared to the SMR (steam methane reforming) process for natural gas. The process can be further adapted to Coal-To-Liquids(CTL) plants to utilize by-products from the Fischer-Tropsch reactor, resulting in a higher (over 10%) yield of liquid fuels and a significant reduction in operational costs by handling carbon dioxide separation more efficiently. Additionally, optimizing iron oxide particles has led to the development of strong particles durable at high temperatures, demonstrated to maintain full oxygen transfer capacity over a 100 cycles of reduction and oxidation.

Potential Applications:

  • Centralized large scale hydrogen production: Uses in oil refining, ammonia manufacture
  • Coal to Liquid (CTL) plants
  • Suitable for making Fe particles which can be used for hydrogen storage and producing electricity via fuel cells

Advantages:

  • Integrated CO2 separation, with no costly separation techniques. Provides ready to sequester CO2 stream by design, offering several environmental benefits
  • Fuel flexibility, allowing for all kinds of gaseous carbonaceous fuels such as syngas, producer gas, natural gas, and fuel cell exhaust
  • Can help tailor H2/CO ratio of syngas to any desired level
  • High hydrogen production efficiency (80-90%)
  • Over 15% costs savings over traditional processes
  • Easily adaptable for integration with CTL plants, resulting in cost reductions
  • Produces low cost Fe2O3 composite particles, shown to undergo more that 100 redox cycles without loss in activity

Novel Organic Light Emitting Diode (OLED) Technologies for Lighting and Display Applications

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Summary:

Researchers at The Ohio State University have developed a comprehensive portfolio of Organic Light Emitting Diode (OLED) technologies that include novel materials and device architectures as platforms for functional devices and for device manufacturing. These developments improve material stability over time while improving their performance such that the required voltage can be reduced and improved electroluminescence can be obtained with reduced power consumption. The bilayer device structure improves device quantum efficiency and brightness due to charge confinement and exciplex emission at the emitting polymer interface. Beyond advancements in the materials themselves, novel device architectures have been developed which are independent of the materials used. These advancements may be of significant value in simplifying manufacturing, thereby accelerating the displacement of LCD and plasma display technologies as well as the displacement of traditional incandescent and fluorescent lighting sources. The associated patent portfolio consists of 8 patent families with a total of 11 issued U.S. patents and 39 associated national stage filings (spanning all US cases). A listing of all issued U.S. patents can be found below.

Potential Applications:

  • Conformal, designable, and color-variable interior and exterior lighting for residential and commercial environments
  • Power and weight sensitive lighting and display applications (e.g. aircraft interior lighting, portable display backlighting)
  • Portable lighting devices such as flashlights
  • Light, ultra-thin, flexible displays with rich colors viewable from very wide angles
  • Body-wearable lighting and display applications
  • Nearly endless list of potential applications

Advantages:

  • More energy efficient lighting source compared to incandescent and fluorescent approaches
  • Color quality matches or surpasses conventional approaches in lighting and display applications
  • Estimated useful life is approximately 17-25 times longer than incandescent lighting and nearly twice as long as linear flourescent lighting (which is commonly used in modern LCD displays)
  • Polymeric material is conformal to a wide range of surface topologies and allows for ultra-thin, flexible displays
  • Low cost, materials-independent architectures have the potential to lower manufacturing costs
  • Adjustable color spectrum