Berlin 2024 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 52: Nitrides: Devices

HL 52.6: Vortrag

Freitag, 22. März 2024, 11:00–11:15, EW 015

Optically pumped UVC VCSELs — •Estrella Torres Vasquez¹, Joachim Ciers¹, Nelson Rebelo¹, Filip Hjort¹, Michael Bergmann¹, Sarina Graupeter², Giulia Cardinali², Johannes Enslin², Tim Wernicke², Michael Kneissl^2,3, and Åsa Haglund¹ — ¹Chalmers University of Technology, Gothenburg, Sweden — ²Technical University of Berlin, Berlin, Germany — ³Ferdinand-Braun-Institut (FBH), Berlin, Germany

We demonstrate optically pumped ultraviolet-C (UVC <280 nm) vertical-cavity surface-emitting lasers (VCSELs) with an accurate cavity length control including a smooth etched N-polar surface. This was enabled by photo-assisted electrochemical etching of an Al_0.45Ga_0.55N sacrificial layer with a Si doping of 4×10¹⁹ cm⁻³. The VCSEL consists of an AlN cavity with 5 Al_0.30Ga_0.70N/Al_0.70Ga_0.3N quantum wells and SiO₂/HfO₂ distributed Bragg reflectors. Photoluminescence measurements show a non-linear output power vs. pump power with a threshold pump power density down to 2 MW/cm² (incident power density) and a strong spectral narrowing down to 50 pm linewidth above threshold. The angular-resolved far-field spectrum changes from parabolic to non-dispersive around threshold with a 9^∘ full width at half maximum. The main lasing wavelength only varies ∼1.2 nm between different UVC VCSELs across a 1.4 mm x 0.9 mm area, indicating an excellent cavity length control.