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Proceedings Paper

In-situ metrology in multiwafer reactors during MOVPE of AIN-based UV-LEDs (Conference Presentation)
Author(s): Arne Knauer; Frank Brunner; Tim Kolbe; Sylvia Hagedorn; Viola Kueller; Markus Weyers

Paper Abstract

UV-LEDs are of great interest for applications like disinfection, gas sensing, and phototherapy. The cost sensitive LEDs are commonly grown by MOVPE on transparent AlN/sapphire templates. The large thermal and lattice mismatch between AlN and sapphire generates a very high dislocation density (DD) and causes big challenges in strain management. The threading dislocation density should be reduced to the order of low 108cm-2 for high internal efficiency of the AlGaN based UV-LED structures. The TDD will be reduced mainly by dislocation annihilation during the growth of thick Al(Ga)N layers, which is a challenge in terms of strain management. We present how in-situ reflectometry and curvature measurement (EpiCurveTT(at)LayTec) in commercial multiwafer growth reactors helps to optimize the growth processes concerning growth rates, surface roughening and avoidance of layer cracking on 2inch substrates and enhance the reproducibility of epitaxial growth. The growth of up to 3 μm thick planar AlN templates and up-to 10 μm thick AlN/sapphire templates by epitaxial lateral overgrowth of stripe patterned templates for UV-C LED structures will be highlighted. The implementation of different types of AlN/GaN superlattices for the subsequent growth of up to 5μm thick Al0.5Ga0.5N layer for UVB LED structures will be shown. Correlations to ex-situ measurements like X-ray diffraction and TEM analysis of defects in the LED structures will be shown. Some challenges of in-situ control through very narrow viewports as in Close Coupled Showerhead reactors will be discussed as well as the influence of silicon doping on curvature and dislocation density in Al(Ga)N layers.

Paper Details

Date Published: 20 April 2017
PDF: 1 pages
Proc. SPIE 10124, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XXI, 101240Q (20 April 2017); doi: 10.1117/12.2253867
Show Author Affiliations
Arne Knauer, Ferdinand-Braun-Institut (Germany)
Frank Brunner, Ferdinand-Braun-Institut (Germany)
Tim Kolbe, Ferdinand-Braun-Institut (Germany)
Sylvia Hagedorn, Ferdinand-Braun-Institut (Germany)
Viola Kueller, Ferdinand-Braun-Institut (Germany)
Markus Weyers, Ferdinand-Braun-Institut (Germany)


Published in SPIE Proceedings Vol. 10124:
Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XXI
Jong Kyu Kim; Michael R. Krames; Li-Wei Tu; Martin Strassburg, Editor(s)

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