High extraction efficiency ultraviolet light-emitting diode
| DWPI Title: UV LED used for e.g. water purification and data storage, has p- and n-type structures comprising aluminum gallium nitride layers, and multiple quantum wells which emit light with specific degree of polarization |
| Abstract: Ultraviolet light-emitting diodes with tailored AlGaN quantum wells can achieve high extraction efficiency. For efficient bottom light extraction, parallel polarized light is preferred, because it propagates predominately perpendicular to the QW plane and into the typical and more efficient light escape cones. This is favored over perpendicular polarized light that propagates along the QW plane which requires multiple, lossy bounces before extraction. The thickness and carrier density of AlGaN QW layers have a strong influence on the valence subband structure, and the resulting optical polarization and light extraction of ultraviolet light-emitting diodes. At Al>0.3, thinner QW layers (<2.5 nm are preferred) result in light preferentially polarized parallel to the QW plane. Also, active regions consisting of six or more QWs, to reduce carrier density, and with thin barriers, to efficiently inject carriers in all the QWs, are preferred. |
| Use: UV LED used for water purification, bio-agent detection, and data storage. |
| Advantage: The UV-LED has high extraction efficiency due to the tailored aluminum gallium nitride quantum wells, and ensures high device efficiency by controlling quantum well composition and thickness. |
| Novelty: UV LED has p-and n-type structures comprising aluminum gallium nitride layers to form p-n junction, and multiple quantum wells arranged between p-and n-type structures. Each quantum well comprises an aluminum gallium nitride quantum well layer sandwiched between opposing aluminum gallium nitride barrier layers, and quantum well layers are compressively strained having an aluminum composition, thickness, and carrier density. The multiple quantum wells emit light with a degree of polarization of more than 0.3 so that it is polarized parallel to plane of quantum well layers. |
| Filed: 9/8/2014 |
| Application Number: US14480072A |
| Tech ID: SD 13085.0 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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