Electronic properties of Si-doped AlxGa1-xN with aluminum mole above 80%
F. Mehnke1, X.T. Trinh2, H. Pingel1, T. Wernicke1, E. Janzen2, N.T. Son2, and M. Kneissl1,3
Published in:
J. Appl. Phys., vol. 120, no. 14, pp. 145702 (2016).
Abstract:
The dependence of the activation energy as well as the energetic levels of the neutral charge state the DX center of the Si donor in AlxGa1-xN:Si samples on aluminum content and SiH4/III ratio investigated by electron paramagnetic resonance (EPR) measurements, Van-der-Pauw resistivity measurements, and Hall-effect measurements. It was found by EPR measurements that the distance of the neutral charge state of the Si donor from the conduction band increases with increasing aluminum content from 61 meV for x=0.82 to 106 meV for x=0.89. Additionally, the formation of a DX center below the neutral charge state which is deepening from 6 meV for x=0.82 to 58 meV for x=0.89 is observed. This results in a linearly increasing activation energy with increasing aluminum content from 67 meV for x=0.82 to 164 meV for x=0.89. This is consistent with the activation energies as determined by Hall-effect measurements showing a linear increase from 24 meV x=0.85 to 211 meV for x=0.96, as well as the activation energies as determined by Van-der- resistivity measurements. By varying the SiH4/III ratio we observed a formation of a minimum resistivity in accordance with the room temperature charge carrier density. However, no clear dependence of the activation energy was observed. EPR measurements of samples with a high SiH4/III ratio hint to an increased incorporation probability of a deep secondary donor species which might explain increase in resistivity.
1 Institut für Festkörperphysik, Technische Universität Berlin, EW 6-1, Hardenbergstr. 36, 10623 Berlin, Germany
2 Department of Physics, Chemistry and Biology (IFM), Semiconductor Materials, University of Linköping, 58183 Linköping, Sweden
3 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Strasse 4, 12489 Berlin, Germany
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