Berlin 2024 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 49: Semiconductor Lasers II
HL 49.6: Talk
Thursday, March 21, 2024, 16:30–16:45, EW 561
Gain characteristics of AlGaN quantum wells for UVC laser diodes application — •Giulia Cardinali1, Alexander Schulz1, Sebastian Kölle2, Friedhard Römer2, Bernd Witzigmann2, Norman Susilo1, Daniel Hauer Vidal1, Martin Guttmann1, Tim Wernicke1, and Michael Kneissl1,3 — 1Technische Universität Berlin, Insitute of Solid State Physics, Berlin, Germany — 2University of Erlangen-Nürnberg (FAU), Department of Electrical Engineering, Erlangen, Germany — 3Ferdinand-Braun-Institut (FBH), Berlin, Germany
UVC laser diodes have small size, low cost and high output power, providing a viable alternative to 266 nm frequency-quadrupled solid-state lasers. Thick AlGaN single quantum wells (SQW) with large confinement factors are advantageous for UVC devices, and can achieve relatively low thresholds despite the large polarization fields. In this study, AlGaN UVC optically pumped lasers with a SQW active region with thickness between 3 nm and 12 nm were fabricated with m-plane resonators and cavity lengths between 600 µm and 1400 µm. The threshold power density decreases with increasing QW width, with the lowest value of 1.3 MW/cm2 for a 9 nm SQW laser. All the samples exhibited positive gain for all QW widths, with the highest differential gain for the 9 nm SQW, in correspondence of the minimum of the threshold. The high gain and low threshold of thick AlGaN QWs are explained by k·p simulations, showing a large electron-hole wavefunction overlap at high carrier density in thick wells, where a high contribution to the gain also comes from excited state transitions.
Keywords: AlGaN; edge-emitting lasers; UVC; nitrides; optical gain