Regensburg 2022 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 10: Nitrides
HL 10.10: Vortrag
Montag, 5. September 2022, 17:30–17:45, H34
Distributed polarization doping for 265 nm UVC LEDs — •Massimo Grigoletto1,2, Sarina Graupeter1, Anton Muhin1, Fedir Bilchenko1, Eviathar Ziffer1, Norman Susilo1, Tim Wernicke1, and Michael Kneissl1,2 — 1Technische Universität Berlin, Institute of Solid State Physics, 10623 Berlin, Germany — 2Ferdinand-Braun-Institut, 12489 Berlin, Germany
Distributed polarization doping (DPD) for optoelectronic devices with high aluminium mole fractions in AlGaN alloys is a promising concept for achieving high hole densities and simultaneously minimize the light absorption on the p-side.
A continuous grading downward from an higher to a lower aluminium mole fraction in the alloy composition of the AlGaN layer, leads to a steady piezoelectric polarization change creating a negative net charge that is compensated by free holes. In this way, dopant-free without thermal activation is possible, which can exhibit orders of magnitude higher hole densities than comparable magnesium impurity doped AlGaN layers.
In this study we investigate the influence of the DPD graded layer design on the electro optical properties and material properties of 265 nm AlGaN-based LEDs by varying the thickness and aluminium gradient. The LED heterostructures with and without the different DPD-layers are grown by metal organic vapor phase epitaxy and analyzed by electroluminescence measurements, transmission spectroscopy, high resolution X-ray diffraction, atomic force microscopy, capacitance voltage spectroscopy and determination of sheet and contact resistance.