InGaN and InAlN alloys grown in the entire composition range by plasma assisted molecular beam epitaxy

Eleftherios Iliopoulos 1Alexandros Georgakilas 1Emmanouil Dimakis 1Adam Adikimenakis 1Katerina Tsagaraki 1Maria G. Androulidaki 1Nikolaos T. Pelekanos 2

1. Microelectronics Research Group, Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, and University of Crete, Physics Department (MRG), Heraklion 71110, Greece
2. Microelectronics Research Group, Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, and University of Crete, Department of Materials Science and Technology, Heraklion, Greece

Abstract

InGaN and InAlN ternary alloy films, spanning the entire composition range, were grown successfully by radiofrequency plasma assisted molecular beam epitaxy and their properties were investigated by high resolution x-ray diffraction (HR-XRD), photoluminescence (PL), optical transmission and reflection spectroscopies.
Phase separation was fully suppressed kinetically in the RF-MBE grown films. XRD spectra exhibited well defined, narrow single diffraction peaks in all cases. However, growth of high structural quality thick films proved difficult for the case of InAlN with compositions close to 50% AlN.
In the case of InGaN films the determined in-plane biaxial strain exhibited a change of sign, from positive (compressive) to negative (tensile) for compositions larger than 60% InN and reached the value of 2.6x10-3 for 90% InN, a value close to the one measured for InN films grown under similar conditions.
Optical bandgap data of InGaN films were fitted well in the entire composition range with a constant value of bowing coefficient, equal to 2.4 eV. On the other hand, InAlN exhibited a dependence of the bowing coefficient on the AlN composition. In both cases the results were extrapolated to an InN bandgap between 0.9 and 1.0 eV, which is higher than the 0.7 to 0.8 eV value of the photoluminescence observed in our InN samples.

 

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Presentation: oral at E-MRS Fall Meeting 2005, Symposium A, by Eleftherios Iliopoulos
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-20 19:58
Revised:   2009-06-07 00:44