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Electrical Efficiency

Massachusetts Institute of Technology

Seamless Hybrid-integrated Interconnect NEtwork (SHINE)

The Massachusetts Institute of Technology (MIT) will develop a unified optical communication technology for use in datacenter optical interconnects. Compared to existing interconnect solutions, the proposed approach exhibits high energy efficiency and large bandwidth density, as well as a low-cost packaging design. Specifically, the team aims to develop novel photonic material, device, and heterogeneously integrated interconnection technologies that are scalable across chip-, board-, and rack-interconnect hierarchy levels. The MIT design uses an optical bridge to connect silicon semiconductors to flexible ribbons that carry light waves. The optical bridge scheme employs single-mode optical waveguides with small modal areas to minimize interconnect footprint, increase bandwidth density, and lower power consumption by using active devices with small junction area and capacitance. The architecture builds all the active photonic components (such as semiconductor lasers, modulators, and detectors) on the optical bridge platform to achieve low energy-per-bit connections. After developing the new photonic packaging technologies, and interconnection architectures, the team's final task will be to fabricate and test a prototype interconnect platform to validate the system models and demonstrate high bandwidth, low power, low bit-error-rate data transmission using the platform.

Michigan State University

Diamond Diode and Transistor Devices

Michigan State University (MSU) will develop high-voltage diamond semiconductor devices for use in high-power electronics. Diamond is an excellent conductor of electricity when boron or phosphorus is added-or doped-into its crystal structures. It can also withstand much higher temperatures with higher performance levels than silicon, which is used in the majority of today's semiconductors. However, current techniques for growing doped diamond and depositing it on electronic devices are difficult and expensive. MSU is overcoming these challenges by using an innovative, low-cost, lattice-etching method on doped diamond surfaces, which will facilitate improved conductivity in diamond semiconductor devices.

MicroLink Devices

High-Power Vertical-Junction Field-Effect Transistors Fabricated on Low-Dislocation-Density GaN by Epitaxial Lift-Off

MicroLink Devices will engineer affordable, high-performance transistors for power conversion. Currently, high-performance power transistors are prohibitively expensive because they are grown on expensive gallium nitride (GaN) semiconductor wafers. In conventional manufacturing processes, this expensive wafer is permanently attached to the transistor, so the wafer can only be used once. MicroLink Devices will develop an innovative method to remove the transistor structure from the wafer without damaging any components, enabling wafer reuse and significantly reducing costs.

Monolith Semiconductor, Inc.

Advanced Manufacturing and Performance Enhancements for Reduced Cost Silicon Carbide MOSFETS

Monolith Semiconductor will utilize advanced device designs and existing low-cost, high-volume manufacturing processes to create high-performance silicon carbide (SiC) devices for power conversion. SiC devices provide much better performance and efficiency than their silicon counterparts, which are used in the majority of today's semiconductors. However, SiC devices cost significantly more. Monolith will develop a high-volume SiC production process that utilizes existing silicon manufacturing facilities to help drive down the cost of SiC devices.

National Renewable Energy Laboratory

Negating Energy Losses in Organic Photovoltaics Using Photonic Structures

NREL and the University of Colorado (CU) are developing a way to enhance plastic solar cells to capture a larger part of the solar spectrum. Conventional plastic solar cells can be inexpensive to fabricate but do not efficiently convert light into electricity. NREL is designing novel device architecture for plastic solar cells that would enhance the utilization of parts of the solar spectrum for a wide array of plastic solar cell types. To develop these plastic solar cells, NREL and CU will leverage computational modeling and advanced facilities specializing in processing plastic PVs. NREL's plastic solar cell devices have the potential to exceed the power conversion efficiencies of traditional plastic solar cells by up to threefold.

Northeastern University

A Universal Converter for DC, Single-phase AC, and Multi-phase AC Systems

Princeton Optronics

Ultra-High Speed VCSELs for Optical Communication

Princeton Optronics, Inc. will develop a new device architecture for optical interconnect links, which communicate using optical fibers that carry light. The maximum speed and power consumption requirement of data communication lasers have not changed significantly over the last decade, and state-of-the-art commercial technology delivers only 30 Gigabits per second (Gb/s). Increasing this speed has been difficult because the current devices are limited by resistance and capacitance constraints. Princeton Optronics will develop a novel device architecture to improve the data transfer and reduce the power consumption per bit by a factor of 10. They will use their expertise in vertical-cavity surface-emitting lasers (VCSELs) to design and build unique quantum wells - and increase the speed and lower the power consumption. The team aims to demonstrate speeds greater than 50 Gb/s, and perhaps 250 Gb/s devices in the future.

Princeton University

Fast Electrochemical Acoustic Signal Interrogation for Battery Lifetime Extrapolation

The Princeton University team is developing a non-invasive, low-cost, ultrasonic diagnostic system to determine battery state-of-health and state-of-charge, and to monitor internal battery defects. This system links the propagation of sound waves through a battery to the material properties of components within the battery. As a battery is cycled, the density and mechanical properties of its electrodes change; as the battery ages, it experiences progressive formation and degradation of critical surface layers, mechanical degradation of electrodes, and consumption of electrolyte. All of these phenomena affect how the sound waves pass through the battery. There are very few sensing techniques available that can be used during battery production and operation which can quickly identify changes or faults within the battery as they occur. As an ARPA-E IDEAS project, this early stage research project will provide proof of concept for the sensing technique and build a database of acoustic signatures for different battery chemistries, form factors, and use conditions. If successful, this ultrasonic diagnostic system will improve battery quality, safety, and performance of electric vehicle and grid energy storage systems via two avenues: (1) more thorough and efficient cell screening during production, and (2) physically relevant information for more informed battery management strategies.

Quora Technology, Inc.

Reliable and Self-Clamped GaN Switch: 1.5 kV Lateral JFET scalable to 100A

Quora Technology, Inc. will develop a new type of gallium nitride (GaN) transistor, called a lateral junction field effect transistor (LJFET) and investigate its reliability compared to other types of transistors, such as SiC junction field effect transistors (JFETs) and GaN-based high electron mobility transistors (HEMTs). Quora's innovative LJFET design distributes and places the peak electric field away from the surface, eliminating a key point of failure that has plagued GaN HEMT devices and prevented them from achieving widespread use. If successful, this project will deliver a 1.5kV, 10A GaN LJET devices that would be scalable to 100A. The devices will be fabricated on thick, uniform GaN layers deposited on a coefficient of thermal expansion matched 8-inch QST engineered platform that is compatible with current silicon processing equipment - reducing the cost of the devices. The uniform GaN layers on the large area platform will increase the yield of the devices further decreasing the cost. Finally, the thick GaN will enable the higher voltage standoff and improve the thermal management of the devices.

Sandia National Laboratory

High Voltage Re-grown GaN P-N Diodes Enabled by Defect and Doping Control

Sandia National Laboratory

MVDC/HVDC Power Conversion with Optically-Controlled GaN Switches

Sandia National Laboratories will develop a new type of switch, a 100kV optically controlled switch (often called photoconductive semiconductor switch or PCSS), based on the WBG semiconductors GaN and AlGaN. The capabilities of the PCSS will be demonstrated in high-voltage circuits for medium and high voltage direct current (MVDC/HVDC) power conversion for grid applications. Photoconductivity is the measure of a material's response to the energy inherent in light radiation. The electrical conductivity of a photoconductive material increases when it absorbs light. The team will first measure the photoconductive properties of GaN and AlGaN in order to assess if they operate similarly to gallium arsenide, a conventional semiconductor material used for PCSS, demonstrating sub-bandgap optical triggering and low-field, high-gain avalanche providing many times as many carriers by the electric field as created by the optical trigger. These two effects provide a tremendous reduction in the optical trigger energy required to activate the switch. The team will then design and fabricate GaN and AlGaN-based photoconductive semiconductor switches. The team predicts that WBG PCSS will outperform their predecessors with higher switch efficiency, the ability to switch at higher voltages, and will turn-off and recover faster, allowing for a higher frequency of switching. Ultimately, this will enable high-voltage switch assemblies (50-500kV) that can be triggered from a single, small driver (e.g. semiconductor laser). These modules will be substantially smaller (~10x) and simpler than existing modules used in grid-connected power electronics, allowing the realization of inexpensive and efficient switch modules that can be used in DC to AC power conversion systems on the grid at distribution and transmission scales.

SixPoint Materials, Inc.

GaN Homoepitaxial Wafers by Vapor Phase Epitaxy on Low-Cost, High-Quality Ammonothermal GaN Substrates

SixPoint Materials will create low-cost, high-quality vertical gallium nitride (GaN) substrates for use in high-power electronic devices. In its two-phase project, SixPoint Materials will first focus on developing a high-quality GaN substrate and then on expanding the substrate's size. Substrates are thin wafers of semiconducting material used to power devices like transistors and integrated circuits. SixPoint Materials will use a two-phase production approach that employs both hydride vapor phase epitaxy technology and ammonothermal growth techniques to create its high-quality, low-cost GaN substrates.

Soraa, Inc.

Large-Area, Low-Cost Bulk GaN Substrates for Power Electronics

Soraa will develop a cost-effective technique to manufacture high-quality, high-performance gallium nitride (GaN) crystal substrates that have fewer defects by several orders of magnitude than conventional GaN substrates and cost about 10 times less. Substrates are thin wafers of semiconducting material needed to power devices like transistors and integrated circuits. Most GaN-based electronics today suffer from very high defect levels and, in turn, reduced performance. In addition to reducing defects, Soraa will also develop methods capable of producing large-area GaN substrates-3 to 4 times larger in diameter than conventional GaN substrates-that can handle high-power switching applications.

Teledyne Scientific & Imaging, LLC

Integrated Power Chip Converter for Solid-State Lighting

Teledyne is developing cost-effective power drivers for energy-efficient LED lights that fit on a compact chip. These power drivers are important because they transmit power throughout the LED device. Traditional LED driver components waste energy and don't last as long as the LED itself. They are also large and bulky, so they must be assembled onto a circuit board separately which increases the overall manufacturing cost of the LED light. Teledyne is shrinking the size and improving the efficiency of its LED driver components by using thin layers of an iron magnetic alloy and new gallium nitride on silicon devices. Smaller, more efficient components will enable the drivers to be integrated on a single chip, reducing costs. The new semiconductors in Teledyne's drivers can also handle higher levels of power and last longer without sacrificing efficiency. Initial applications for Teledyne's LED power drivers include refrigerated grocery display cases and retail lighting.

The Research Foundation for State University of New York, on behalf of SUNY Polytechnic Institute

Demonstration of PN-junctions by Implant and Growth techniques for GaN

Transphorm, Inc.

High-Performance GaN HEMT Modules for Agile Power Electronics

Transphorm is developing transistors with gallium nitride (GaN) semiconductors that could be used to make cost-effective, high-performance power converters for a variety of applications, including electric motor drives which transmit power to a motor. A transistor acts like a switch, controlling the electrical energy that flows around an electrical circuit. Most transistors today use low-cost silicon semiconductors to conduct electrical energy, but silicon transistors don't operate efficiently at high speeds and voltage levels. Transphorm is using GaN as a semiconductor material in its transistors because GaN performs better at higher voltages and frequencies, and it is more energy efficient than straight silicon. However, Transphorm is using inexpensive silicon as a base to help keep costs low. The company is also packaging its transistors with other electrical components that can operate quickly and efficiently at high power levels-increasing the overall efficiency of both the transistor and the entire motor drive.

University of California, Berkeley

IceNet for FireBox

The University of California, Berkeley will develop a new datacenter network topology that will leverage the energy efficiency and bandwidth density through the integration of silicon photonics into micro electro-mechanical system (MEMS) switches. Today's datacenter architectures use server nodes (with processor and memory) connected via a hierarchical network. In order to access a remote memory in these architectures, a processor must access the network to get to a particular server node, gaining access to the local memory of that server. This requires the remote server processor to be awake at all times in order to service the remote request. The processor-to-memory network has many stages and long latency, which results in significant energy waste in processor and memory idling on both sides of the network. The IceNet network is designed to achieve ultra-low latency connectivity between processor nodes and memory, drastically reducing energy wasted during system idling. A key component to the team's design is their LightSpark active laser power-management system. In addition to guiding the laser power where it is needed, the LightSpark module enables both wavelength and laser redundancy, increasing the robustness of the system. In total, the IceNet network will enable dramatic improvements in datacenter system efficiency, allowing for fine-grain power control of processors, links, and memory and storage components.

University of California, San Diego

LEED: A Lightwave Energy-Efficient Datacenter

The University of California, San Diego will develop a new datacenter network based on photonic technology that can double the energy efficiency of a datacenter. Their LEED project mirrors the development of CPU processors in PCs. Previous limitations in the clock rate of computer processors forced designers to adopt parallel methods of processing information and to incorporate multiple cores within a single chip. The team envisions a similar development within datacenters, where the advent of parallel lightwave networks can act as a bridge to more efficient datacenters. This architecture leverages advanced photonic switching and interconnects in a scalable way. Additionally, the team will add a low-loss optical switch technology that routes the data traffic carried as light waves. They will also add the development of packaged, scalable transmitters and receivers that can be used in the system without the need for energy-consuming optical amplification, while still maintaining the appropriate signal-to-noise ratio. The combination of these technologies can create an easily controllable, energy-efficient architecture to help manage rapidly transitioning data infrastructure to cloud-based services and cloud-based computing hosted in datacenters.

University of California, Santa Barbara

High Efficiency Quantum-Dot Photonic Integrated Circuit Technology Epitaxially Grown on Silicon

The University of California at Santa Barbara will develop a new technology for optical communication links. Optical interconnects transfer data by carrying light through optical fibers, and offer higher bandwidths than copper with higher efficiency and, consequently, reduced heat losses. However, short-reach optical interconnects are not widely used because of their higher costs and larger device footprints. Production costs of these interconnects could be reduced by using silicon-based fabrication technologies, but silicon is not suited for fabricating lasers, a key ingredient. In contrast III-V semiconductors, are well-suited for fabricating highly efficient lasers, but at a high cost. The team plans to combine these components to create III-V lasers, grown on a silicon substrate, harnessing both the low cost of silicon and the superior laser of the III-V semiconductor. However, growing the III-V laser material directly on silicon is difficult due to incompatibilities in their crystal structures. The team aims to overcome this challenge by implementing nanostructures called "quantum dots" as the light producing material and by growing the structure on patterned silicon substrates to help contain potential defects.

University of California, Santa Barbara

Laser-Based Solid State Lighting 

The University of California, Santa Barbara will develop a gallium nitride (GaN) laser-based white light emitter with no efficiency droop at high current densities. The team's solution will address the efficiency and cost limitations of LEDs. Laser diodes do not suffer efficiency droop at high current densities, and this allows for the design of lamps using a single, small, light-emitting chip operating at high current densities. Using a single chip reduces system costs compared with LEDs because the system uses less material per chip, requires fewer chips, and employs simplified optics and a simplified heat-sink. The chip area required for LED technologies will be significantly reduced using laser-based solid state lighting. This technology will also enable highly controllable beams of light that cannot be achieved with LEDs. The goal of the project is to develop a 1,000 lumen laser-based white light emitter with the efficiency of at least 200 lm/W and a cost of $0.25/klm.

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