Hamburg 2001 – scientific programme

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HL: Halbleiterphysik

HL 24: Poster II

HL 24.31: Poster

Thursday, March 29, 2001, 10:30–19:00, Rang S\ 3

Optical investigation of Al_xGa_1−xN alloys grown on AlN epitaxial films — •N. Teofilov¹, K. Thonke¹, L. Kirste², D. Ebling², R. Sauer¹, and K. Benz² — ¹Abteilung Halbleiterphysik Universität Ulm, 89069 Ulm — ²Freiburger Materialforschungszentrum, Universität Freiburg, 79104 Freiburg

Al_xGa_1−xN/AlN heterostructures were grown on c-plane sapphire by RF-plasma enchanced molecular beam epitaxy. The Al mole fraction was varied over the whole composition range (0<x<1). Low temperature reflection and cathodoluminescence measurements have been carried out in the energy range from 3.0 eV to 6.2 eV at liquid helium temperatures in order to study the dependence of the optical band-gap energy on the alloys composition. We find a bowing parameter of (2.3 ± 0.4) eV at 10 K. The energy dispersion of the refractive index and the thicknesses of both, the AlGaN active layer and AlN buffer layer, have been obtained from numerical simulations of the reflectivity spectra, using a two-layer (substrat/interlayer/active layer) model.