Sunovia and EPIR Announce IR Sensor and Solar Cell BreakthroughsApril 7, 2008
The technology and manufacturing developments result in cost reductions that further enable the use of IR sensors in large commercial markets and provide a new paradigm for multi-junction solar cells.
SARASOTA, FL /PRNewswire-FirstCall/ -- Sunovia Energy Technologies Inc. is pleased to announce technology and manufacturing breakthroughs by EPIR Technologies Inc. (EPIR). EPIR's research and development efforts have formed a cornerstone for products that enabled the U.S. military's night-vision superiority. The breakthroughs address cost reductions that further enable infrared (IR) sensors for use in large commercial markets and provide a new paradigm for multi-junction solar cells. The new solar cell technology will have high efficiencies at lower costs by leveraging less expensive IR system materials and manufacturing processes that have been developed with more than $30 million dollars of investment over the past 25 years. Sunovia and EPIR believe that a successful strategy is to leverage the ongoing commercialization and continued sale of advanced IR sensors while directly transferring these breakthrough IR technologies to the commercialization of next-generation solar cells. A portion of the core technologies behind EPIR's breakthroughs are disclosed in U.S. Patent No. 6,657,194, "Multispectral Monolithic Infrared Focal Plane Array Detectors."
Dr. T. S. Lee, who joined EPIR from the Microphysics Laboratory (MPL) at the University of Illinois at Chicago (UIC), was responsible for many of the technical breakthroughs needed for this work. Dr. Lee stated, "We surmounted many technical hurdles, such as the molecular beam epitaxial (MBE) growth of CdTe and HgCdTe layers on heterostructural silicon wafers containing readout integrated circuits to successfully mate II-VI semiconductor materials with Si for device fabrication for x-ray and IR detection. I am very excited that this technology also has solar-power applications, where it can play a major role in reducing the world's demands for fossil fuels."
"Owning the Night" has been a cornerstone of maintaining the U.S. Army's tactical superiority through advanced technology, plans, and tactics. A key element in the equation is maintaining and expanding a clear technological edge in the area of IR imaging—night vision. Improving sensitivity, decreasing noise, enhancing reliability, and lowering costs represent important success factors in the effort. Central to the work has been the very innovative and extensive research and development work of professor Siva Sivananthan and his teams at UIC and EPIR. The most significant advances over the past two and a half decades in the area of advanced materials for IR imaging have come out of the labs of UIC and EPIR.
In the area of night vision, enabling successful nighttime operations lies in the ability to widely disseminate cutting-edge imaging technology to as many of the soldiers as possible involved in nighttime operations. An impediment to accomplishing this goal has been the high cost of the IR imaging devices. The delicate nature and high cost of the MCT IR light-detection material itself has been the prime culprit. The advance in depositing a very thin layer of ultra-sophisticated material directly on the read-out circuitry represents the removal of a significant hurdle toward achieving substantially lower cost finished devices and systems.
Specifically, EPIR's achievement is a MCT IR focal plane array (FPA) grown directly on a thin cadmium telluride (CdTe) epilayer, which in turn was grown directly on a silicon (Si) read-out integrated circuit (ROIC). Thus, the IR FPA that generates the electrical signals to be converted into a digital picture was directly and monolithically connected to the ROIC that interprets those signals to create a picture without a need for externally applied contacts and interconnects. The monolithic integration of an MCT FPA with its ROIC simultaneously realized a key differentiator within IR-detector technology and formed a proof of concept for the fabrication of a novel high-efficiency, two-junction, and two-terminal solar cell.
This breakthrough resulted from many years of intensive work on the MBE growth of CdTe on Si and of MCT on CdTe, first at MPL and then by many of the same scientists and engineers at EPIR. One of the major challenges overcome was the cleaning of the Si ROICs without damaging the contacts or resorting to temperatures high enough to damage the ROICs. Another was the direct deposition of high-quality single-crystal CdTe directly on the Si ROICs, with excellent current collection by the ROICs despite the small fractional area available for growth on ROICs. Yet others were the deposition of high-quality single-crystal MCT on the CdTe and the dopant activation and device processing to create an FPA, all at temperatures low enough not to harm the ROIC. Overcoming these challenges clearly demonstrated the ability to fabricate multijunction, two-terminal high-efficiency solar cells, such as CdTe/Si cells or other more complex cells based on CdTe/Si, and went far beyond that demonstration. The breakthrough and much other work by EPIR on IR FPAs has clearly demonstrated the ability to fabricate such solar cells with the necessary current matching and efficient current collection, without a buffer layer between the Si and the CdTe, with or without a thin zinc telluride tunneling barrier, as needed for current matching.
Monolithic integration such as that achieved by EPIR obviates all of the deficiencies associated with the usual bump binding between the contact on each pixel of an FPA and the corresponding ROIC contact, eliminates complex and low-yield processes, eliminates thermal mismatches, and thus allows much larger formats and greater resolution, creates compact systems with lower heat loads, and reduces costs by increasing yield. Nonmonolithic FPAs, whether grown on Si or on cadmium zinc telluride (CZT), suffer from many deficiencies because of the necessary bump-bonding. The bump-bonding requires extensive packaging, is susceptible to vibration failures, and is plagued by parasitic capacitances and inductances that degrade the sensitivity and bandwidth of the FPAs.
The material grown and the monolithic devices fabricated were subjected to a number of tests and passed all of them. For example, the measured carrier recombination time, which is the primary measure of material quality and must be long enough to allow the currents generated by incident light to be efficiently collected, was excellent. Also the measured dynamic FPA impedance at the standard operating temperature of 80°K reached 106 Ohm-cm2 at zero bias for growth on Si and 105 Ohm-cm2 for growth on ROICs, again excellent values. Finally, the device operability was found to be excellent, although a small fraction of the pixels lost operability during device fabrication.
In addition to defense IR imaging applications and markets, much larger markets exist in providing a night vision/IR imaging capability in security, law enforcement, and spectroscopic imaging applications. Sunovia believes this significant cost-saving advance will go far in enabling the widespread adoption of the technology into these new markets and applications.
Sunovia and EPIR have exclusively partnered to commercialize solar, IR and x-ray technologies for the renewable energy, night-vision, and medical and scientific markets. Sunovia is the exclusive marketer of all products, technologies, and intellectual properties that are developed by EPIR, and currently owns a significant equity interest in EPIR. EPIR is the world leader in R&D on materials and devices for IR detection and imaging for night vision, missile tracking, space exploration, and other applications.
Sunovia announced that Donna Webb has been appointed to the position of vice president of operations. The company mistakenly indicated that Mrs. Webb had been appointed to the position of chief operations officer in a press release dated March 2008.
About Sunovia Energy
Sunovia Energy Technologies Inc. is a Sarasota, FL–based renewable energy and energy conservation company working to develop one of the most advanced and cost-effective CdTe solar cell technologies ever created. Sunovia is also the owner of the proprietary EvoLucia LED lighting product line. The incredibly energy-efficient solid-state lighting solutions have received CE, FCC, TUV, and IP23 regulatory approvals, and are now being marketed worldwide.
Sunovia owns a significant equity interest in Illinois-based EPIR Technologies Inc., one of the most advanced IR sensor and IR imaging companies in the world. "EPIR's knowledge, experience, and expertise in the growth of CdTe, HgCdTe, and other II-VI semiconductors equal or exceed any other company in the world. Their prowess in this area is unmatched and has been endorsed by the award of unprecedented congressional funds for the development of a manufacturing capability for CdTe on Si and the award of a patent for growing CdTe directly on a Si readout integrated circuit." EPIR and Sunovia have a network of close collaborative relationships with the major Defense Department and industrial labs involved in IR detection and imaging, including the Army Research Laboratory, the Night Vision Electronic Sensors Directorate, BAE Systems, Lockheed Martin, DRS, Raytheon, Rockwell, Texas Instruments, and other laboratories around the world.
More information about this exclusive partnership may be viewed in the company's filings with the Securities and Exchange Commission.
The Sunovia Energy logo is a registered service mark of Sunovia Energy Technologies Inc. in the U.S. and/or other countries. Sunovia Energy products and services are provided by Sunovia Energy Technologies Inc.
EPIR Technologies Inc. (EPIR) is one of the most advanced IR sensor and infrared imaging companies in the world. "EPIR's knowledge, experience, and expertise in the growth of CdTe, HgCdTe, and other II-VI semiconductors equals or exceeds that of any other company in the world.
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