Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 29: III-V Semiconductors I (mainly Nitrides)
HL 29.9: Vortrag
Dienstag, 27. März 2012, 11:45–12:00, EW 201
Growth of (2021) AlGaN, GaN and InGaN by metal organic vapor phase epitaxy — •S. Ploch1, T. Wernicke1, J. Rass1, M. Pristovsek1, M. Weyers2, and M. Kneissl1,2 — 1TU Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin — 2Ferdinand-Braun-Institut Leibniz Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
Green InGaN-based laser diodes on (2021) GaN substrates have recently demonstrated performances exceeding those of conventional (0001) oriented devices. However little is known regarding the growth parameters. We have investigated growth of AlGaN, GaN and InGaN on (2021) GaN substrates by MOVPE. Smooth GaN layers with a rms roughness <0.5 nm were obtained by low growth temperatures and reactor pressures. The layers exhibit undulations along [1014] similar to the GaN substrate. AlGaN and InGaN layers exhibit an increased surface roughness. Undulation bunching was observed and attributed to reduced adatom surface mobility due to the binding energy of Al and the low growth temperature for InGaN respectively or strain relaxation. AlGaN and InGaN heterostructures on (2021) GaN relax by layer tilt accompanied by formation of misfit dislocations, due to shear strain of the unit cell. This relaxation mechanism leads to a reduced critical layer thickness of (2021) AlGaN layers and InGaN multi quantum wells (MQW) in comparison to (0001). PL spectral broadening of 230 meV of (2021) InGaN single QWs emitting at 415 nm can be reduced by increased growth temperature or increased number of QWs with reduced thickness.