Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 17: Poster I
HL 17.49: Poster
Montag, 25. Februar 2008, 16:30–19:00, Poster D
Optical investigation of doped and undoped AlN layers — •Günther M. Prinz1, Ingo Tischer1, Martin Schirra1, Martin Feneberg1, Sarad B. Thapa2, Ferdinand Scholz2, Yoshitaka Taniyasu3, Makoto Kasu3, Rolf Sauer1, and Klaus Thonke1 — 1Institut für Halbleiterphysik, Universität Ulm, D-89069 Ulm — 2Institut für Optoelektronik, Universität Ulm, D-89069 Ulm — 3NTT Basic Research Laboritories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, 243-0198, Japan
Aluminum nitride (AlN) represents the upper end of the technologically interesting ternary alloy system AlGaN with an ultra-wide direct band gap of approximately 6.1 eV at liquid helium temperature. Here doped and undoped AlN layers on sapphire and SiC were investigated by means of cathodoluminescence and Raman spectroscopy. All layers show intense near-band edge luminescence at approx. 6eV. This luminescence shifts down as a function of the Si doping concentration but is independent for growth on the two different substrates or for different growth temperatures. Concomitantly, the E2high-Raman mode shifts to lower wave numbers, indicating tensile strain in the doped AlN layers. Correlating these results quantitatively we show that the near-band edge luminescence shift is exclusively due to tensile strain and is not a result of a reduced band gap through high doping concentrations as suggested in literature.