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Highly Wrinkled Metal Thin Films Using Lift-Off Layers

Wearable electronics are becoming a popular way of integrating personal healthcare with continuous, remote health monitoring, yet current devices are bulky and exhibit poor electronic performance. Wrinkled metal thin films can be utilized for their thin, flexible profiles, which conform well to the skin. Researchers at UCI have developed a novel method using specialized materials that results in wrinkled metal thin films that have enhanced mechanical and electrical performance.

Hybrid Growth Method for Improved III-Nitride Tunnel Junction Devices

Hybrid growth method for III-nitride tunnel junction devices that uses metal-organic chemical vapor deposition (MOCVD) to grow one or more light-emitting or light-absorbing structures and ammonia-assisted or plasma-assisted molecular beam epitaxy (MBE) to grow one or more tunnel junctions.

Frequency Discriminator-based Phase Noise Filter (PNF) for Ultra-Clean LO/Clock

Researchers at the University of California, Davis have developed a delay line frequency discriminator and phase detector (PD)/charge pump (CP)-based phase noise filter (PNF) circuit that achieves wide bandwidth, high sensitivity, and reliable integration at 10 GHz.

Terahertz (THz) Interconnect Semiconductor Realizes High Energy and Bandwidth Density

Researchers at the University of California, Davis have developed a sub-THz interconnect semiconductor to realize high-energy efficiencies and high bandwidth densities through planar silicon process-compatible channels and couplers.

Hybrid SPST Switch Delivers High Isolation Over an Ultra-wide Bandwidth

Researchers at the University of California, Davis have developed a hybrid, complementary metal-oxide semiconductor (CMOS) mm-wave, single-polar single-throw (SPST) switch that combines the wide bandwidth features of a distributed structure and the compact implementation of coupled lump elements for an area-efficient layout.

Printable Repulsive-Force Electrostatic Actuator Methods and Device

Flexible electrostatic actuators are well designed for a range of commercial applications, from small micro-mechanical robotics to large vector displays or sound wall systems. Electrostatic actuation provides efficient, low-power, fast-response driving and control of movable nano-, micro-, and macro-structures. While commercially available electrostatic actuators have the requisite high levels of mechanical energy / force for some applications, their energy requirements are typically orders of magnitude higher than what is needed in large-area, low-power applications. Moreover, conventional approaches to these types of electrostatic actuators have limited design geometries and are prone to reliability issues like electrical shorts. To address these problems, researchers at the University of California, Berkeley, have experimented with planar electrostatic actuators using novel printing and electrode patterning and engineering techniques. The team has demonstrated a repulsive-force electrostatic actuator device (100 mm x 60 mm achieved) with extremely high field strength and high voltage operation and without insulator coatings or air breakdown.

RF-Powered Micromechanical Clock Generator

Realizing the potential of massive sensor networks requires overcoming cost and power challenges. When sleep/wake strategies can adequately limit a network node's sensor and wireless power consumption, then the power limitation comes down to the real-time clock (RTC) that synchronizes sleep/wake cycles. With typical RTC battery consumption on the order of 1µW, a low-cost printed battery with perhaps 1J of energy would last about 11 days. However, if a clock could bleed only 10nW from this battery, then it would last 3 years. To attain such a clock, researchers at UC Berkeley developed a mechanical circuit that harnesses squegging to convert received RF energy (at -58dBm) into a local clock while consuming less than 17.5nW of local battery power. The Berkeley design dispenses with the conventional closed-loop positive feedback approach to realize an RCT (along with its associated power consumption) and removes the need for a sustaining amplifier altogether. 

Low-variability, Self-assembled Monolayer Doping Methods

Semiconductor materials are fundamental materials in all modern electronic devices. Continuous demand for faster and more energy-efficient electronics is pushing miniaturization and scaling to unprecedented levels. Controlled and uniform doping of semiconductor materials with atomic accuracy is critical to materials and device performance. In particular, junction depth and dopant concentration need to be tightly controlled to minimize contact resistance, as well as variability effects due to random dopant fluctuations in the channel. Conventional doping methods such as ion implantation is imprecise and can have large variability effect. Moreover, energetic introduction of dopant species will often cause crystal damage, leading to incompatibility with nanostructured-materials and further performance degradation. To address these problems, researchers at the University of California, Berkeley, have experimented with an alternative approach to a wafer-scale surface doping technique first developed at the UC Berkeley in 2007. The team has demonstrated a controlled approach for monolayer doping (MLD) in which gas phase dopant-containing molecules form low-variability, self-assembled monolayers (SAM) on target semiconductor surfaces.

Increased Light Extraction with Multistep Deposition of ZnO on GaN

A method of depositing ZnO on III-nitride materials using a multistep approach involving the deposition of a thin seed layer followed by the deposition of a thicker bulk layer.

Enhanced Light Extraction LED with a Tunnel Junction Contact Wafer Bonded to a Conductive Oxide

A method of bonding transparent conductive oxides on III-nitride materials using wafer bonding techniques.

III-Nitride Tunnel Junction with Modified Interface

A method for improving the performance of semipolar III-nitride light-emitting devices. 

Apparatus and Method for 2D-based Optoelectronic Imaging

The use of electric fields for signaling and manipulation is widespread, mediating systems spanning the action potentials of neuron and cardiac cells to battery technologies and lab-on-a-chip devices. Current FET- and dye-based techniques to detect electric field effects are systematically difficult to scale, costly, or perturbative. Researchers at the University of California Berkeley have developed an optical detection platform, based on the unique optoelectronic properties of two-dimensional materials that permits high-resolution imaging of electric fields, voltage, acidity, strain and bioelectric action potentials across a wide field-of-view.

A New Methodology For 3D Nanoprinting

Researchers at the University of California, Davis have discovered a novel protocol to enable 3D printing with nanometer precision in all three dimensions using polyelectrolyte (PE) inks and atomic force microscopy.

Frequency Reference For Crystal Free Radio

Wireless sensors and the Internet of Things (IoT) have the potential to greatly impact society. Millimeter-scale wireless microsystems are the foundation of this vision. Accordingly, to realize this potential, these microsystems must be extremely low-cost and energy autonomous. Integrating wireless sensing systems on a single silicon chip with zero external components is a key advancement toward achieving those cost and energy requirements.  Almost all commercial microsystems today use off-chip quartz technology for precise timing and frequency reference. The quartz crystal (XTAL) is a bulky off-chip component that puts a size limitation on miniaturization and adds to the cost of the microsystem. Alternatively, MEMS technology is showing promising results for replacing the XTAL in space-constrained applications. However, the MEMS approach still requires an off-chip frequency reference and the resulting packaging adds to the cost of the microsystem.  To achieve a single-chip solution, researchers at UC Berkeley developed: (1) an approach to calibrating the frequency of an on-chip inaccurate relaxation oscillator such that it can be used as an accurate frequency reference for low-power, crystal-free wireless communications; and (2) a novel ultra-low power radio architecture that leverages the inaccurate on-chip oscillator, operates on energy harvesting, and meets the 1% packet error rate specification of the IEEE 802.15.4 standard. 

Improved 3D Transistor

This case helps reinvent the transistor by building on the success of Berkeley’s 3D FinFET/Trigate/Tri-Gate methods and devices, with increased focus on the negative capacitance of the MOS-channel and ferroelectrics, and an unconventional effective oxide thickness approach to the gate dielectric. Proof of concept devices have been demonstrated at 30nm gate length and allow for use of thinner ferroelectric films than 2D negative capacitance transistors (e.g. see http://digitalassets.lib.berkeley.edu/techreports/ucb/text/EECS-2014-226.pdf ). The devices also performed at low operating voltage which lowers operating power.

Improved Anisotropic Strain Control in Semipolar Nitride Devices

A method to control the anisotrophy of strain in semipolar nitride-based active layers of optoelectronic devices while maintaining high device performance and efficiency.

Method for Improved Surface of (Ga,Al,In,B)N Films on Nonpolar or Semipolar Subtrates

A method for improving the growth morphology of (Ga,Al,In,B)N thin films on nonpolar or semipolar (Ga,Al,In,B)N substrates that uses an inert carrier gas such as N2.

Highly Efficient, Heterogeneous, Hybrid-Integrated Optoelectronic Device Structure with Conductive and Low Loss Interface

Researchers at the University of California Davis have developed a fabrication technique that allows conductive wafer bonding between heterogeneous semiconductor materials with low optical losses and low electrical losses (low voltage and resistance).

Tunable White Light Based on Polarization-Sensitive LEDs

Polarized white LEDs that can improve system efficiency by removing the need for an external polarizer.

High Light Extraction Efficiency III-Nitride LED

A III-nitride light emitting diode (LED) with increased light extraction from having at least one textured surface of a semipolar or nonpolar plane of a III-nitride layer of the LED.

High-Efficiency, Mirrorless Non-Polar and Semi-Polar Light Emitting Devices

An (Al, Ga, In)N light emitting device in which high light generation efficiency occurs by fabricating the device using non-polar or semi-polar GaN crystals.

Reactor with Carbon Fiber Materials for Improved III-Nitride Growth

A reactor for growing high-quality group III-nitride crystals using carbon-carbon fiber composites in low oxygen ambient environments.

Methods of Forming Dopant-free, Asymmetric Heterocontact Structures

Worldwide photovoltaic capacity reached 178GW in 2014 and with an additional 55GW slated for deployment. With installed capacity projected to more than double by 2020, solar power is anticipated to become one of the largest sources of electricity, with solar photovoltaics representing about 16 percent of total. Current photovoltaic cell technology is based on crystalline silicon (c-Si) which generally uses doped homojunctions to create pathways of asymmetrical conductivity for electron and hole transport. This approach is limited by a host of interrelated optical, transport and recombination-based losses, most notably parasitic absorption and Auger recombination. Moreover, there are technological challenges and scaling problems associated with doping under high temperatures and with small contact fractions. To address these problems, researchers at the University of California, Berkeley, have developed advanced contact structures, which replace these doped regions, using alkali metal fluorides and metal oxides. Early lab results are reporting competitive cell efficiencies approaching 20%. These cells were fabricated using low-temperatures and no lithography, introducing potential for gains on both sides of the cost-to-performance ratio for c-Si photovoltaics.

Monolithic 3D Printing of Smart Objects

The number of interconnected sensors and actuators are expected to grow beyond thousands of units per person by 2020, and new manufacturing processes will be required for personalization and seamless integration of such devices into our surrounding objects. One major general challenge for manufacturers is with scaling production of mechanically sophisticated and tailored objects while maintaining or improving efficiency. 3D printing may be an excellent candidate for manufacturing at scale as it enables on-demand and rapid manufacturing of user-defined objects. However, traditional 3D approaches have a unique set of challenges due to incompatible processing approaches with metals with plastics. To address these challenges, researchers at UC Berkeley have developed novel 3D printing techniques for fully-integrated smart objects that embed liquid metal-based passive/active components and silicon integrated circuits to achieve greater system-level functionalities. For demonstration, UC researchers created a form-fitting glove with embedded programmable heater, temperature sensor, and the associated control electronics for thermotherapeutic treatment, specifically tailored to an individual’s body. These novel processes can enable assembly of electronic components into complex 3D architectures, which may provide a new platform for creating personalized smart objects in volume.

Planar, Nonpolar M-Plane III-Nitride Films Grown on Miscut Substrates

A method for growing planar nonpolar III-nitride films that have atomically smooth surfaces without any macroscopic surface undulations. 

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