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In this article we proposed a modified transmission line model method to analyze non-Ohmic contact. It can differentiate the contact resistance while the current flows into and out of the contact. When the earlier two factors are equal, this method degenerate to traditional method. By this method, we obtained contact parameters for both p-GaN and n-GaN and revealed the validity of this method. To further study the contact characteristics and transportation mechanism between alloyed Ni/Au and p-GaN, we also measured barrier information at different temperature and current. The result indicates the hole passes through the barrier by thermionic emission and the barrier may lowered by image force. [ABSTRACT FROM AUTHOR]

Abstract: The Ga1− x Mn x N epitaxial films were grown by metalorganic chemical vapor deposition (MOCVD) with tricarbonyl (methycyclopentadienyl) manganese ((MCP)2Mn) as dopant source. Magnetic measurements indicate that the films are n-type conductivity (x=0.01), ferromagnetic ordering with Curie temperature above room temperature. The magnetic moment per Mn atom decreases when the Mn concentration changes from 0.01 to 0.03. Magneto-transport properties were performed in the temperature range of 2–300K. The magneto-resistance (MR) changes from negative effect to positive effect with increasing temperature. The negative MR effect at low temperature is due to the reduction of the magnetic scattering of the Mn ions under the applied magnetic field. Furthermore, the zero-field-cooled (ZFC)/field-cooled (FC) and MR behavior at low temperature confirm that the ferromagnetism and paramagnetism coexist in Ga1− x Mn x N films. [Copyright &y& Elsevier]