Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 50: Poster II

HL 50.12: Poster

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

Anisotropy of the Γ-point electron effective mass in hexagonal InN — •T. Chavdarov¹, T. Hofmann², V. Darakchieva³, H. Lu⁴, W.J. Schaff⁴, and M. Schubert² — ¹Institut für Experimentelle Physik II, Universität Leipzig, Leipzig, Germany — ²CMRA, University of Nebraska-Lincoln, Lincoln, USA — ³Department of Physics and Measurement Technology, Linköping University, Sweden — ⁴Department of Electrical and Computer Engineering, Cornell University, USA

InN recently attracted much attention due to the availability of high-quality samples. Particularly the unexpected low band gap of 0.6 to 0.7 eV has triggered new experiments, vivid debates, and many reconsiderations, but still information on fundamental material parameters like the anisotropy of the Γ-point wurtzite-structure effective electron mass are lacking. Only few experimentally determined values on the isotropically averaged effective mass value of hexagonal InN exist so far. In this contribution we employ generalized magnetooptic ellipsometry in the far-infrared spectral range to determine the effective mass parallel m_e,∥^∗ and perpendicular m_e,⊥^∗ to the c axis, the free electron concentration N, and parallel µ_e,∥^∗ and perpendicular µ_e,⊥^∗ optical mobility parameters in thin InN layers with different N in the range between 5×10¹⁷ cm⁻³ to 2×10¹⁹ cm⁻³ without electrical contacts. The samples were grown by molecular beam epitaxy on sapphire substrates. While our isotropically averaged effective mass values are in good agreement with recently reported values, we observe a distinct anisotropy of the effective mass, with m_e,⊥^∗ > m_e,∥^∗, which is in good agreement with recent LDA band-structure calculation results reported by Carrier and Wei, JAP 97, 033707 (2005).