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Optical properties of InN grown on Si(111) substrate
|Egidijus Sakalauskas 1, Pascal Schley 1, Ruediger Goldhahn 1, Javier Grandal 2, Miguel A. Sanchez-Garcia 2, Enrique Calleja 2, Arantxa Vilalta Clemente 3, Pierre Ruterana 3|
1. Technische Universität Ilmenau, Institut für Physik, PF 100565, Ilmenau 98684, Germany
A comprehensive characterization of the optical properties of wurtzite InN films grown on Si(111) is presented. InN layers were deposited by plasma assisted molecular beam epitaxy. Two types of InN grown on Si(111) substrate samples are investigated in this work: InN on AlN/Si(111) and InN on GaN/AlN/Si(111). The crystalline quality of the layers was investigated by means of X-ray diffraction. Surface morphology was measured by atomic force microscope (AFM). Spectroscopic ellipsometry between 0.56 eV and 9.8 eV (synchrotron radiation) is applied in order to determine the dielectric function (DF), i.e. the absorption related properties, while conventional photoluminescence yields the emission characteristics. For InN grown on Si(111) substrate, the absorption onset is slightly shifted to higher energies with respect to films on GaN/sapphire substrates studied for comparison. The electron density is obtained from the size of the Burstein-Moss shift. The analysis includes the non-parabolicity of the conduction band and the influence of strain on the band gap.
Despite the higher carrier concentration for InN on Si(111) samples, strongly pronounced optical transitions due to critical points of the band structure are found in the high-energy part of the spectra. The fitted transition energies are in excellent agreement with the results for films grown on sapphire. It emphasizes the already promising quality of the films on silicon and makes feasible that Si with its several advantages such as large size, high quality, low cost and high potential for integration with well-developed Si-based devices can serve as a substrate for InN epitaxy.
We acknowledge the support of the EU under Grant agreement N°:PITN-GA-2008-213238 (RAINBOW project: Initial Training Network of the 7th RTD Framework).
Presentation: Oral at E-MRS Fall Meeting 2009, Symposium A, by Egidijus Sakalauskas
See On-line Journal of E-MRS Fall Meeting 2009
Submitted: 2009-05-11 10:20 Revised: 2009-06-07 00:48