In-situ metrology in multiwafer reactors during MOVPE of AIN-based UV-LEDs (Conference Presentation)

Arne Knauer; Frank Brunner; Tim Kolbe; Sylvia Hagedorn; Viola Kueller; Markus Weyers

doi:10.1117/12.2253867

20 April 2017 In-situ metrology in multiwafer reactors during MOVPE of AIN-based UV-LEDs (Conference Presentation)

Arne Knauer, Frank Brunner, Tim Kolbe, Sylvia Hagedorn, Viola Kueller, Markus Weyers

Proceedings Volume 10124, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XXI; 101240Q (2017) https://doi.org/10.1117/12.2253867
Event: SPIE OPTO, 2017, San Francisco, California, United States

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.

Conference Presentation

Citation Download Citation

Arne Knauer, Frank Brunner, Tim Kolbe, Sylvia Hagedorn, Viola Kueller, and Markus Weyers "In-situ metrology in multiwafer reactors during MOVPE of AIN-based UV-LEDs (Conference Presentation)", Proc. SPIE 10124, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XXI, 101240Q (20 April 2017); https://doi.org/10.1117/12.2253867

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KEYWORDS

Light emitting diodes

Aluminum nitride

Metrology

Epitaxial lateral overgrowth

Phototherapy

Reflectometry

Sapphire

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