Regensburg 2010 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 34: Poster I: III-V Semiconductors
HL 34.18: Poster
Tuesday, March 23, 2010, 18:30–20:30, Poster D2
Comparison of c- and a-plane aluminum nitride by cathodoluminescence and positron annihilation spectroscopy — •Martin von Kurnatowski1, Barbara Bastek1, Matthias Wieneke1, Thomas Hempel1, Frank Bertram1, Armin Dadgar1, Juergen Christen1, Alois Krost1, Jussi-Matti Mäki2, and Filip Tuomisto2 — 1Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Germany — 2Department of Applied Physics, Helsinki University of Technology, Espoo, Finland
Due to its large band gap of more than 6 eV AlN is an important material for III-nitride-based electronic and optoelectronic devices operating in the ultraviolet region. It has already been successfully applied in AlN/AlGaN heterostructures. However, for the reduction of internal polarization fields non- and semipolar III-nitride layers are mandatory, which has been attracting interest in research in the past few years.
In this contribution a set of c-plane and a-plane AlN samples grown under identical growth conditions was investigated. The growth temperature as well as the V/III-ratio was varied for each orientation. Plan-view FE-SEM-images show a brain-like surface structure of the c-plane samples. The surface quality improves with increasing growth temperature. Spatially averaged low temperature CL-spectra reveal a more intense near band edge emission from the c-plane AlN indicating higher material quality than in the a-plane samples. In addition to that, the luminescence attributed to Al-vacancies is less intense in the c-plane samples. These measurements are in agreement with the findings in positron annihilation spectroscopy.