Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 50: Poster II

HL 50.18: Poster

Donnerstag, 30. März 2006, 16:30–19:00, P3

Optical properties of InN films — •Christoph Cobet¹, Patrick Vogt², Munise Rakel^1,2, Rüdiger Goldhahn³, Massimo Drago², Antje Vollmer⁴, Wolfgang Richter², and Norbert Esser¹ — ¹ISAS - Institute for Analytical Sciences, Albert-Einstein-Str. 9, D-12489 Berlin — ²Institute of Solid State Physics, TU Berlin, Hardenbergstr. 36, D-10623 Berlin — ³Institute of Physics, TU Ilmenau, Weimarer Straße 25, D-98648 Ilmenau — ⁴BESSY-GmbH, Albert-Einstein Str. 15, D-12489 Berlin

We report on measurements of the dielectric function of hexagonal InN in a broad spectral range from 0.5-12eV by means of ellipsometry. An a-plane InN(11-20) layer grown by MBE in the Cornell University was utilized to determine the ordinary and extraordinary part of the dielectric tensor. We find a huge anisotropy between both components, where specific absorption structures differ in energy position or disappear in the extraordinary component. All structures will be attributed to particular interband transitions in comparison with GaN. Our experiments indicate also a strong influence of surface contaminations, which finally effect the position of the measured band gap as well. In order to analyze the surface degradation, we performed SXPS before and after a thermal annealing of MOVPE-grown InN samples in UHV. The InN(0001) surface after transfer into UHV gives rise to clear C1s and O1s core-level contributions, the latter originating from hydroxides due to water contamination of the surface in air. Thermal annealing at 573K is sufficient to remove carbon and hydroxide components. But stable oxide contributions could not be removed.