| NSF Org: |
ECCS Division of Electrical, Communications and Cyber Systems |
| Recipient: |
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| Initial Amendment Date: | July 19, 2016 |
| Latest Amendment Date: | July 19, 2016 |
| Award Number: | 1648705 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Dominique Dagenais
ddagenai@nsf.gov (703)292-2980 ECCS Division of Electrical, Communications and Cyber Systems ENG Directorate for Engineering |
| Start Date: | July 15, 2016 |
| End Date: | June 30, 2017 (Estimated) |
| Total Intended Award Amount: | $100,000.00 |
| Total Awarded Amount to Date: | $100,000.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
1850 RESEARCH PARK DR STE 300 DAVIS CA US 95618-6153 (530)754-7700 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
One Shields Avenue Davis CA US 95616-5270 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | EPMD-ElectrnPhoton&MagnDevices |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.041 |
ABSTRACT
Title: EAGER: A Single Materials System that Could Finally Realize Light Emitting Devices with Optimal Chromaticity
Abstract
Nontechnical Description:
In spite of the tremendous progress made in the last 55 years in developing visible Light Emitting Diodes (LEDs) for applications that require red, green, and blue emitters, at least two different materials systems are still required to realize systems having only the approximate hue and colorfulness properties (chromaticity) that is required. This is a major problem because having to use two different materials technologies adds a large cost to the production of displays that have red, green, and blue elements (pixels), such as scoreboards at public arenas. Furthermore, the current technology does not produce optimal chromaticity in the display systems. Neither of these systems can efficiently produce the required "true" green color. Thus, the combination of high cost and non-optimal chromaticity has prevented the use of pixelated displays for color images for TV systems; modern TV systems use inexpensive white emitting LEDs as the light source to visualize the liquid crystal pixelated TV image. Therefore, it is the goal of this research to perform both fundamental materials science and construct exploratory devices that will realize a unified technology to reduce the manufacturing production costs and improve chromaticity for visible display applications. The broader implications of a successful outcome of this project are threefold. First, it will increase the breadth of the application markets for visible displays, especially advanced pixelated display systems, including TV systems. Second, it will add to the fundamental materials science and device engineering knowledge of a relatively unexplored materials system. Finally, low cost LEDs with optimal chromaticity will enable "tuned" white light sources without the current need to coat blue-emitting LEDs with phosphors and filtering.
Technical Description:
The goal of this proposal is to develop a lattice-matched, heterovalent compound semiconductor materials system and epitaxy technology to realize efficient and integrated LEDs that will cover the entire spectrum from near IR to blue wavelengths, especially "true green" (555 nm wavelength). The targeted materials system and epi-technology is (ZnSe)x(GaAs)1-x epilayers on ZnSe or GaAs substrates and Molecular Beam Epitaxy (MBE), respectively, and employs a novel method to develop homogeneous epilayers. The specific aims of this research are to 1) develop a recipe for the growth of ZnSe on GaAs based on the configuration of our MBE system, 2) identify the optimal epitaxial growth procedure of quaternary alloys of (ZnSe)x(GaAs)1-x, and 3) fabricate Double-Heterojunction (DH) devices with (ZnSe)x(GaAs)1-x composition tuned for "true green" LEDs. With the knowledge gained in this research, a single commercial materials system and a unified fabrication technology that can produce a wide spectral range of light emitting devices, laser, and solar concentrator chips can be realized. Equally important, the results are expected to have a positive translational impact because it is probable that success in unifying light emitters using a (ZnSe)x(GaAs)1-x system would have a huge impact on the photonics community both in industry and academia, especially those who would produce multi-colored pixel arrays. This in turn will open up new avenues for the community to explore both new heterovalent epitaxy principles and new applications that take advantage of integration of lattice-matched heterovalent direct band gap materials systems.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Intellectual Merit:
The intellectual merit of our proposal is clear. The (ZnSe)x(GaAs)1-x system has been studied intermittently since the early 1960s. These studies revealed that this system had properties, such as a band gap range and being nearly lattice matched, that could enable photonic devices with band gap energies that lie within the red, green, and blue LED and laser wavelengths. Unfortunately, these applications were never realized in device technology. Therefore if our project is successful, it will not only elucidate the fundamental epitaxy issues associated with heterovalent compound semiconductor materials, but also enable a new photonic device industry. With the knowledge gained in this research, a single commercial materials system and a unified fabrication technology that can produce a wide spectral range of light emitting devices, laser, and solar concentrator chips can be accomplished. Equally important, the results are expected to have a positive translational impact because it is probable that success in unifying light emitters using a GaAsZnSe system would have a huge impact on the light emitting industry, especially those who would produce multi-colored pixel arrays.
Broader Impacts:
First, our research program in itself will allow graduate and undergraduate students to be trained in multidisciplinary research areas, encompassing device physics, optoelectronic devices, Molecular Beam Epitaxy (MBE), materials science, and device fabrication. Particularly, this research provides a unique teaching opportunity, as the students involved will have firsthand experience learning about MBE system design and operation. This newly refurbished system is the only MBE system at UC-Davis. In addition, the graduate students will have the opportunity to participate in conferences, publish in peer-reviewed journals, and mentor undergraduate students. The PI will design projects that include undergraduate students interested in semiconductor physics and materials science to work with the graduate students on their projects. Equally important is the impact of the success of our research on the photonics community both in industry and academia. Our results will open up new avenues for the community to explore both new heterovalent epitaxy principles and new applications that take advantage of integration of lattice-matched heterovalent direct band gap materials systems.
Last Modified: 10/12/2017
Modified by: Zhaoquan Zeng
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