Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1532048 | Materials Science and Engineering: B | 2006 | 11 Pages |
Abstract
Growth, fabrication, and the electrical and optical characterization of ultraviolet light emitting diodes and their components, including AlxGa1âxN films, quantum wells (QWs), and ohmic contacts, and the problems encountered in the process integration of these components have been investigated. Ni/Au ohmic contacts with specific contact resistivities of 2.2 Ã 10â4 and 2.0 Ã 10â2 Ω cm2 were achieved on annealed, Mg-doped ([Mg] â¼Â 5 Ã 1019 cmâ3), p-type GaN layers that had been cleaned in HCl at 85 °C and on the backside of the SiC substrates after annealing in nitrogen, respectively. The emission intensity of the diodes increased with an increase in the number of Al0.06Ga0.94N/Al0.10Ga0.90N QWs and with the use of Si-doped n-type barrier layers. The highest intensities of the principle emission at 353 nm were measured at all values of the injection current in the device with a p-type carrier-blocking layer at the top of the QWs; this device also exhibited the highest values of light output power. Growth of an n-type carrier-blocking layer at the bottom of the QWs had an adverse effect on their characteristics. A broad peak centered at â¼540 nm exhibited yellow luminescence and was present in the spectra acquired from all the devices. This peak is attributed to absorption of the ultraviolet emission by and re-emission from the p-GaN and/or to the luminescence from the AlGaN within QWs by current injection.
Related Topics
Physical Sciences and Engineering
Materials Science
Electronic, Optical and Magnetic Materials
Authors
Ji-Soo Park, Zachary J. Reitmeier, Daryl Fothergill, Xiyao Zhang, John F. Muth, Robert F. Davis,