Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 12: Group-III-Nitrides: Optical Properties I
HL 12.6: Vortrag
Montag, 22. März 2010, 15:15–15:30, H15
Cathodoluminescence microscopy analysis of structural and optical properties of HVPE ELO-AlN layers — •Martin von Kurnatowski1, Barbara Bastek1, Juergen Christen1, Thomas Hempel1, Frank Bertram1, Hideto Miyake2, Yusuke Katagiri2, Kazuki Okuura2, and Kazumasa Hiramatsu2 — 1Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Germany — 2Department of Electrical and Electronical Engineering, Mie University, Japan Institute of Solid State
Aluminum nitride is a promising candidate for solid state electronic and optical applications in the deep UV due to its large direct bandgap. However, there is a mismatch between the lattice constants and thermal expansion coefficients of AlN and conventional substrates. Consequently, a high density of dislocations and micro-cracks occurs. The approach of "epitaxial lateral overgrowth" (ELO) has already lead to a drastic reduction of this problem in GaN and AlGaN.
We investigate the microscopic, optical, and structural properties of HVPE-ELO-AlN layers with thicknesses of up to 25 µm. The ELO pattern consists of 1.3 µm wide trenches which were etched into the Sapphire leaving ridges of 2 µm widths. Integral CL spectra show a dominant near band edge (NBE) emission at 6.105 eV at coalescence height. Towards the surface the NBE peak shifts about 18 meV to lower energies. Right at the surface the near band edge energy is modulated by only 5 meV with the periodicity of the underlying trench-pattern.