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Thermal annealing effects on the electrical and structural properties of Ni/Mo Schottky contacts on n-type GaN have been investigated by current-voltage (I-V), capacitance-voltage (C-V), Secondary ion mass spectrometer (SIMS), and X-ray diffraction (XRD) techniques. The extracted Schottky barrier height (SBH) of the as-deposited contacts was found to be 0.66 eV (I-V), 0.74 eV (C-V). However, both measurements indicate that the barrier height slightly increases when the contacts are annealed at 300 and 400 8C. Experimental results indicate that high quality Schottky contact with barrier height and ideality factor of 0.75 eV (I-V), 0.96 eV (C-V), and 1.13, respectively, can be achieved under 1 min annealing at 500 8C in nitrogen atmosphere. Further, it is observed that the barrier height slightly decreases upon annealing at 600 8C. The above observations establish that the Ni/Mo contact exhibited excellent electrical characteristics even after thermal annealing at 600 8C. Based on the SIMS and XRD analysis, the formation of gallide phases at the Ni/Mo/n-GaN interface could be the reason for the improvement of SBH after annealing at 500 8C. The above results indicate that the Ni/Mo contact can be promising for metallization scheme for high-temperature device applications.

We have investigated the temperature-dependent currentvoltage (IV) characteristics of Ti Schottky structure on the Si-on-insulator (SOI) in the temperature range of 175375 K by steps of 25 K. As decreasing temperature, the barrier height and ideality factor of Ti/SOI Schottky contact were found to be decreased and increased, respectively, indicating a considerable deviation from the ideal thermionic emission model in its current conduction mechanism. From the linear relationship between the barrier heights and ideality factors, the homogeneous barrier height was calculated to be 0.76 eV. The mean barrier height of 0.87 eV and the modified Richardson constant value of 30.63 A·cm ¹2 ·K ¹2 were obtained using modified Richardson plot. On the basis of a thermionic emission mechanism with a Gaussian distribution of the barrier heights, the temperature-dependent IV behavior of Ti/SOI Schottky contact was explained in terms of barrier height inhomogeneities at the interface between Ti and SOI.

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