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Ni/Ag as low resistive ohmic contact to p-type AlGaN for UV LEDs

 
: Passow, T.; Gutt, R.; Maier, M.; Pletschen, W.; Kunzer, M.; Schmidt, R.; Wiegert, J.; Luick, D.; Liu, S.; Köhler, K.; Wagner, J.

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Streubel, K.P. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Light-emitting diodes: Materials, devices, and applications for solid state lighting XIV : 26 - 28 January 2010, San Francisco, California, United States
Bellingham, WA: SPIE, 2010 (Proceedings of SPIE 7617)
ISBN: 978-0-8194-8013-2
Paper 76171I
Conference "Light-Emitting Diodes - Materials, Devices, and Applications for Solid State Lighting" <14, 2010, San Francisco/Calif.>
Photonics West Conference <2010, San Franciso/Calif.>
Englisch
Konferenzbeitrag
Fraunhofer IAF ()
UV LEDs; AlGaN; Ni/Ag/Ni; ohmic contact; specific contact resistance; reflectivity

Abstract
Reflective (thick) and semi-transparent (thin) Ni/Ag/Ni contacts were prepared on GaInN-based light-emitting diodes (LEDs) and p-GaN/p-Al(0.15)Ga(0.85)N layer sequences. A light output power enhancement of 41% and forward voltage reduction of 0.59 V were obtained compared to a Ni/Au contact for LEDs emitting at 400 nm with thick p-GaN contact layers. The specific contact resistance of the Ni/Ag/Ni contacts on p-GaN/p-Al(0.15)Ga(0.85)N with varying p-GaN thickness (5-20 nm) were determined by transmission line method and compared to Ni/Au contacts. Low resistive ohmic contacts were obtained for a p-GaN thickness of less than 10 nm. The p-GaN layer can be completely omitted for the reflective Ni/Ag/Ni contact. In addition, reflection and transmission of the Ni/Ag/Ni metallization schemes were investigated in the ultra-violet spectral range. Thick Ni/Ag/Ni and thin Ni/Ag/Ni covered by Al are promising to serve as reflective contacts for ultra-violet LEDs. The former for wavelength around 350 nm and the latter for wavelengths below 350 nm.

: http://publica.fraunhofer.de/dokumente/N-129850.html