Berlin 2008 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 14: Heterostructures
HL 14.6: Talk
Monday, February 25, 2008, 10:45–11:00, ER 164
Influence of barrier thickness on AlInN/AlN/GaN heterostructure properties — •Lars Rahimzadeh Khoshroo1, Christof Mauder1, Ian Booker1, Wanjiao Zhang1, Daniel Wamwangi2, Herbert Horn-Solle3, Joachim Woitok4, Matthias Wuttig2, Andrei Vescan1, Michael Heuken1,5, Holger Kalisch1, and Rolf Jansen1 — 1Institut für Theoretische Elektrotechnik, RWTH Aachen, Kopernikusstr. 16, 52074 Aachen — 2Institute of Physics (1A), RWTH Aachen, Templergraben 55, 52056 Aachen — 3Lehrstuhl für Lasertechnik, RWTH Aachen, Steinbachstr. 15, 52074 Aachen — 4PANalytical B.V., P.O. Box 13, 7600 AA ALMELO, The Netherlands — 5AIXTRON AG, Kackertstr. 15-17, 52072 Aachen
We report on four AlInN/AlN/GaN heterostructures on sapphire substrates with different grown in an AIXTRON metal organic vapor phase epitaxy reactor. High resolution X-Ray diffraction showed 15%In content and X-Ray reflection (XRR) measurements allowed a reliable thickness determination. However, the sample with the thinnest AlInN barrier thickness of 3.2 nm yielded no Hall results due to an increase of sheet resistivity from 372 Ω/* immediately after epitaxy, to 972 Ω/* two weeks later. This increase weakens with increasing barrier thickness. The samples with 4.2 nm, 7.1 nm and 9.3 nm barrier thickness yielded average charge carrier densities and average mobilities (ordered by increasing thickness) of 0.89 x 1013 cm-2, 1.45 x 1013 cm-2, 1.78 x 1013 cm-2 and 1510 cm2/Vs, 1410 cm2/Vs, 1550 cm2/Vs. We assume a stronger detrimental influence on the charge carrier concentration by a changing surface potential at low barrier thicknesses.