Novel Materials Structure for Efficient and Cost-Effective Direct Emission Solid-State Lighting

Direct emission color-mixed lighting based on red-green-blue-amber light emitting diodes could reach efficacies of 325 lumen per watt, provided the so called “green efficiency gap” is closed. Achieving this Department of Energy roadmap target requires materials science breakthroughs in particular for emitters in the amber 570 – 590 nanometer range while simultaneously improving the droop performance of the devices at real-life high operating current densities and temperatures. The objective of our Phase I project is to demonstrate proof-of-concepts for a novel low defect density materials platform that enables the fabrication of efficient amber indium gallium nitride multiple quantum-well heterostructures. Based on the demonstration of efficient amber emission as a result of our Phase I work, we target the development of efficient amber light emitting diodes with high external quantum efficiencies during the SBIR Phase II program. To achieve these objectives, we will develop in Phase I materials structures that will enable the fabrication of amber light emitting diodes with fundamentally lower crystalline defect densities. This materials platform will allow us to create amber emitting indium gallium nitride multiple quantum-wells with reduced the intrinsic electric fields, reduced effective barrier heights in the light emitting region resulting in a high quantum efficiency. We will use optical and structural characterization to validate our development approach, based on which we will create the development plan for the light emitting diode product development during Phase II. The ultimate outcome of our project, if carried through to Phase II and commercialization, will be high efficiency amber indium gallium nitride light emitting diodes, which are so far elusive. Beyond the energy savings in lighting systems, the project advances benefit also emerging displays, thus significantly increasing the energy savings potential.