SKM 2023 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 28: Focus Session: Breakthroughs in wide-bandgap semiconductor laser diodes II

HL 28.5: Vortrag

Mittwoch, 29. März 2023, 16:30–16:45, POT 251

265 nm LEDs and laser heterostructures with p-type distributed polarization doping AlGaN layers — •Massimo Grigoletto^1,2, Sarina Graupeter¹, Verena Montag¹, Jakob Höpfner¹, Luca Sulmoni¹, Tim Wernicke¹, and Michael Kneissl^1,2 — ¹Technische Universität Berlin, Institute of Solid State Physics, 10623 Berlin, Germany — ²Ferdinand-Braun-Institut (FBH), Berlin, Germany

Efficient hole injection in AlGaN-based LEDs and lasers emitting in the ultraviolet (UV) spectral range remains a great challenge. Distributed polarization doped (DPD) p-type AlGaN heterostructures have been developed to overcome this hurdle. By introducing a constant piezoelectric polarization charge along compositionally graded Al_xGa_1−xN layers a high density of free hole carriers can be established even in the absence of Mg dopants. In this study we have investigated the influence of the DPD design on the structural properties and electro-optic characteristics of AlGaN-based LEDs and laser heterostructures emitting near 265 nm. For efficient hole injection p-type Al_xGa_1−xN layers with different Al gradients and thickness have been incorporated and grown by metal organic vapor phase epitaxy. On-wafer measurements of UV-LEDs exhibit forward voltages of 6 V at a dc current of 20 mA and output power of 1 mW comparable to conventionally Mg-doped heterostructures. The LEDs could be operated at high current densities up to 12 kA/cm² in pulsed mode, which shows the DPD is a promising approach for achieving low resistance p-type AlGaN layers with high al mole fractions.