SKM 2023 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 23: Focus Session: Breakthroughs in wide-bandgap semiconductor laser diodes I
HL 23.6: Talk
Wednesday, March 29, 2023, 12:00–12:15, POT 251
P-Cladding Layer Utilizing Polarization Doping for Blue-Violet InGaN Laser Diodes — •Anna Kafar1,2, Muhammed Aktas1, Dario Schiavon1,2, Szymon Stanczyk1,2, Krzysztof Gibasiewicz1,2, Szymon Grzanka1,2, and Piotr Perlin1,2 — 1Institute of High Pressure Physics PAS, Warsaw, Poland — 2TopGaN Ltd., Warsaw, Poland
Nitride-based semiconductors emitters play a crucial role in modern optoelectronics, especially in white LEDs and UV-violet-blue-green laser diodes. However, the p-type doping by Mg acceptor has serious flaws. Spontaneous and piezoelectric polarization present in wurtzite structures can help to overcome the doping problems by means of polarization doping.
In the present work, we study the optoelectronic properties of LED and LD structures with polarization doped p-layers. Electrical characterization of LED structure shows that polarization doping can easily match electrical properties of conventional Mg-doped structures. For the LD structure, we used a double graded p-cladding structure in order to keep the polarization doped structure's hole concentration at the same level as the Mg-doped structure. The electrical characterization of LD shows even lower operating voltage than the Mg-doped sample. Unexpectedly high losses suggest that the structure requires further optimization, but with the use of high-reflectivity coatings we demonstrate lasing with the threshold current of around 500mA at 12°C in CW mode. According to our experience, for fabricating a top metal contact, sub contact doping is indispensable to lower the metal-semiconductor Schottky barrier.