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AlN grown on lens shaped patterned sapphire by HVPE James S. Speck, University of California-Santa Barbara, DMR 0906805.
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AlN grown on lens shaped patterned sapphire by HVPEJames S. Speck, University of California-Santa Barbara, DMR 0906805 Aluminum Nitride provides a promising substrate for AlGaN based UV lasers and light emitting diodes. This is due to the close lattice match, thermal conductivity and transparency in the deep UV region of AlN. Despite this, large area and high quality AlN substrates are not presently available. This has lead to many such devices being grown on GaN or SiC, which absorbs in the UV and significantly hinder device performance. Thus a UV transparent template of thick AlN grown on sapphire could provide a useful substrate. Even further, the patterning on the sapphire leads to higher extraction efficiencies for LEDs. In this work, thick AlN was grown by Hydride Vapor Phase Epitaxy on patterned sapphire. These were fully coalesced, planar and up to 20 microns thick. The growth mode of AlN was also observed as hexagonal pillars initiated on the lenses top. These have clear c-plane and m-plane facets which grow out unto coalescence. Cross sectional SEM images of the AlN films at different growth times of a) no growth b) 3 minutes c) 5 minutes and d) 7 minutes
Impact of High Performance UV EmittersJames S. Speck, University of California-Santa Barbara, DMR 0906805 Ultraviolet optoelectronics have a key role to play in major technological areas such as air and water purification along with communications as with non-line of sight technology. However, current generation UV emitters have had poor performance. This is mainly due to the lack of substrates. This research provides an avenue towards UV transparent and high quality substrates that will allow for improved device performance. These next generation UV emitters will open up new possibilities in a wide range of fields. www.camelbak.com Steri-Pen water purification Water and air purifiers along with non-line of sight communications are a key area of interest for UV emitters.