Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 5: Nitrides: mostly transport properties and recombination processes

HL 5.5: Vortrag

Montag, 31. März 2014, 10:30–10:45, POT 251

Electrical properties of Si-doped AlGaN layers with high aluminum mole fraction — •Harald Pingel1, Frank Mehnke1, Eberhard Richter2, Frank Brunner2, Tim Wernicke1, Christian Kuhn1, Viola Kueller2, Arne Knauer2, Michael Lapeyrade2, Markus Weyers2, and Michael Kneissl1,21Technische Universität Berlin, Institut für Festkörperphysik, Germany — 2Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Berlin, Germany

The electrical properties of Si-doped AlxGa1−xN layers with x > 0.8 were studied by temperature-dependent resistance and Hall measurements. AlxGa1−xN:Si layers with a thickness of 1.2 µm – 1.6  µm were grown by metal organic vapor phase epitaxy using TMAl, TMGa, NH3 as precursors and SiH4 and H2 as dopant source and carrier gas, respectively. A set of samples with different aluminum content and SiH4/III-ratios was investigated. At room temperature the resistivity strongly depends on the aluminum content as well as the SiH4/III-ratio. With increasing aluminium content the resistivity increases from 0.07 Ωcm (x = 0.82) to 4.3 Ωcm (x = 0.95) at a constant SiH4/III-ratio of 2 x 10−5. A distinct minimum in the resitivity was found for a series of SiH4/III-ratios. In order to investigate the cause of this behavior, the charge carrier density, the resistivity and the mobility were measured between 300 K and 720 K. From this, the donor densities and the activation energies were determined. The increase in resistivity for increasing aluminum content could be attributed to an increase in the donor activation energy.

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