Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 4: III-V semiconductors: mainly wells and surfaces
HL 4.11: Vortrag
Montag, 11. März 2013, 12:15–12:30, H15
Si–doping of AlGaN with high aluminum mole fractions by MOVPE — •F. Mehnke1, T. Wernicke1, C. Kuhn1, C. Reich1, J. Stellmach1, F. Brunner2, V. Kueller2, A. Knauer2, M. Weyers2, and M. Kneissl1,2 — 1Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin, Germany — 2Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
Currently one of the main challenges of III–nitride growth is the doping of AlGaN layers with high aluminum mole fraction. Only very few reports exist that show conductive AlGaN:Si layers with an aluminum content of more than 80 %. In this contribution we will present a study on the influence of the aluminum content and the SiH4 supply on the resistivity and the optical properties of silicon doped AlxGa1−xN layers (0.8 < x < 1) grown pseudomorphically on defect reduced AlN–sapphire templates. With increasing aluminum content the resistivity increases exponentially but even for Al0.95Ga0.05N n–conductivity is observable with a resistivity of 4.3 Ω cm. Defect luminescence at 4.4 eV was observed by photoluminescence measurements (PL) becoming more dominant with increasing aluminum content and shifting towards higher energy. By increasing the SiH4 supply during the growth of Al0.82Ga0.18N layers a minimum resistivity of 0.026 Ω cm was obtained. By further increasing the SiH4 supply the resistivity increased strongly. PL show dominant defect luminescence at 3 eV hinting to a compensation by point defect formation e.g. group–III vacancies or vacancy–oxygen–complexes.