Berlin 2024 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 12: Semiconductor Lasers I
HL 12.5: Talk
Monday, March 18, 2024, 16:00–16:15, EW 561
265 nm AlGaN based laser heterostructures using distributed polarization doping — •Lennard Zinsilowski1, Massimo Grigoletto1,2, Jakob Höpfner1, Giulia Cardinali1, Luca Sulmoni1, Tim Wernicke1, and Michael Kneissl1,2 — 1Technische Universität Berlin, Institute of Solid State Physics, 10623 Berlin, Germany — 2Ferdinand-Braun-Institut (FBH), Berlin, Germany
In this study the growth of 265 nm laser diode heterostructures by metalorganic vapor phase epitaxy (MOVPE) implementing distributed polarization doping is investigated. P-type AlGaN layers using distributed polarization doping (DPD) have been recently developed to achieve higher conductivity than p-doped AlGaN:Mg layers, which exhibit increasing resistivities due to increasing ionization energies with higher Al mole fractions. Through a pseudomorphically grown grading of the AlxGa1−xN layers polarization charges are generated in the layer, inducing free hole carriers even in the absence of Mg dopants.
The impact of the active zone growth conditions, structural design and also the DPD design regarding the electrical properties of the laser diodes were studied aiming to achieve high current injection efficiencies. Pulsed on-wafer measurements of 5 µm x 800 µm large devices at a current of 1 A (25 kA/cm2) show voltages around 30 V and a series resistance of 10 Ω. The DPDs show a high durability sustaining current densities of more than 100 kA/cm2 for different geometries. This shows a promising approach towards UV-C laser diodes working on sapphire.
Keywords: MOVPE, AlGaN, laser diodes, UV-C