This Small Business Innovation Research Phase I project will investigate the feasibility of using dopants to significantly improve the reflectivity of a novel grown epitaxial-metal-mirror (GEMM) technology to increase light-emitting diode (LED) device performance and substantially reduce the cost of manufacturing high-brightness III-nitride LEDs. The GEMM technology provides an integrated mirror directly into the epitaxial layers of the LED device, which simplifies manufacturing, reduces cost, and improves yield. Furthermore, the GEMM allows for very precise control over the placement of the mirror in order to take advantage of micro-half-cavity effects. The reflectivity of the first-generation GEMM materials for blue wavelengths is approximately 70%-75% and therefore to further improve the performance and efficiency of the GEMM for blue LEDs and drive market adoption of GEMM-LEDs, we will investigate doping of the GEMM materials to shift the reflectivity spectrum to shorter wavelengths. It is anticipated that these doped-GEMM materials will exhibit reflectivities of 90% or greater in the range of 450 to 460 nm, leading to significantly improved LED performance, while simultaneously reducing manufacturing costs, and will ultimately drive solid-state lighting to become truly commercially competitive.
The broader impact/commercial potential of this project will be the availability of highly energy-efficient solid-state lighting for general consumer use at a cost that is competitive with compact-fluorescent lamps. Currently, LED-based lamps are 5 to 10 times the cost of comparable compact-fluorescent lamps. The market pull for the GEMM technology relies on a projected 35% to 68% lower production cost per lumen for LED chips, which will motivate LED chip manufacturers to purchase GEMM substrates for device growth. Downstream manufactures of LED-based fixtures and manufacturers that integrate light emitters into their products would also greatly benefit from the lower cost and higher performance of GEMM-LEDs. The successful demonstration of enhanced GEMM materials for LEDs during this project has the potential to accelerate the availability of cost-competitive solid-state lighting and drive consumers to embrace LED-based general lighting. In turn, the acceleration of widespread adoption of solid-state LED-based lighting has the potential to reduce the nation's dependence on foreign energy, reduce domestic greenhouse gas emissions, and revitalize the economy of the United States through the creation of "green" jobs and continued technological leadership.
For this NSF Phase I SBIR project, Lightwave Photonics, Inc. (Lightwave) proposed to develop and improve a specialized material layer to be incorporated into high-brightness blue-, green-, and white-light light-emitting diodes (LEDs) to accelerate the widespread adoption of energy-efficient solid-state lighting for the general lighting market. Lightwave’s specialized material layer (known as the "GEMM") has a number of beneficial properties, including being highly reflective and highly conductive, and will enable LED manufacturers to simultaneously improve LED performance and reduce LED manufacturing costs. During this Phase I project, Lightwave successfully developed a manufacturing process for making the GEMM material layers and produced GEMM material layers with significantly improved reflectivity. Reflectivity is a measure of how reflective a material is. Specifically, Lightwave developed an entirely new method of improving the GEMM reflectivity and was able to improve the reflectivity from approximately 80% for blue light (meaning that 80% of the incident blue light will be reflected by the GEMM) to greater than 95% for blue light (meaning that 95% of the incident blue light will be reflected by the GEMM). In addition, this new method enables Lightwave to choose the color of light where the maximum reflectivity occurs, which will provide additional improvements in the performance of the LEDs and allow scientists and engineers to design new and novel LEDs for emerging application areas. The attached photo shows an example of two wafers that have Lightwave’s improved GEMM material manufactured on top. The green colored wafer was designed by Lightwave to be highly reflective for green light, which is why the wafer looks green, and the blue colored wafer was designed by Lightwave to be highly reflective for blue light, which is why the wafer looks blue. Through the commercialization of Lightwave’s GEMM technology, the performance of LEDs will improve and the manufacturing cost of LEDs will decrease. This will ultimately lead to the elimination of the main impediment to widespread adoption of LED solid-state lighting – the upfront cost of LEDs for consumers – and will accelerate the installation of LED solid-state lighting in the United States and the World.
