Regensburg 2022 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 10: Nitrides
HL 10.9: Talk
Monday, September 5, 2022, 17:15–17:30, H34
UVC-LEDs grown on HTA-AlN templates with low dislocation densities and high Si doping for strain management — •Sarina Graupeter1, Michael Gail1, Giulia Cardinali1, Massimo Grigoletto1,2, Sylvia Hagedorn2, Tim Wernicke1, Markus Weyers2, and Michael Kneissl1,2 — 1Technische Universität Berlin, Institute of Solid State Physics, Hardenbergstraße 36, 10623 Berlin, Germany — 2Ferdinand-Braun-Institut (FBH),Gustav-Kirchhoff-Straße 4, 12489 Berlin, Germany
High temperature annealing (HTA) of AlN layers reduces the threading dislocation densitiy of such layers on sapphire substrates below 109cm−2 enabling UVC-LEDs with improved efficiencies. However, the HTA AlN-layers are under high compressive strain after cooling down, which leads to strain relaxation and defect formation during further LED heterostructure growth. Growing Si-doped AlN layers on HTA-AlN can reduce the strain. In this work we investigate the influence of such an AlN:Si-interlayer on the growth of UVC-LEDs emitting at 265nm on HTA AlN/sapphire templates, with different thicknesses and offcut angles. XRD measurements show a reduction of the compressive strain from 0.5% to 0.1% depending on layer thickness. Optical characterization with Photoluminescence and Cathodoluminescence shows, that depending on the layer thickness, defect formation in the form of Ga-rich plateus occurs. Electroluminescence measurements of full UVC-LED structures shows emission powers around 0.75mW at 20mA for the templates with 350nm layer thickness, which is comparable to LEDs grown on more expensive standard templates.