Fabrication and characteristics of Ni-germanide Schottky contacts with Ge

In this study, Ni germanide Schottky barrier diodes on n-Ge (100) substrate were fabricated by sputtering metal Ni on Ge, followed by annealing in N-2 atmosphere from 300 to 500° C in a furnace. The results of x-ray diffraction (XRD) show that the Ni germanide was formed and the diffraction line of (111) was observed in all samples. The structure of Ni germanide is orthorhombic with lattice parameters a=5.811, b=5.381, c=3.428. However, the lines (121) and (002) were observed only in the samples annealed at a temperature higher than 400° C. The influence of annealing temperature on the electrical properties of Ni germanide Schottky barrier diodes on n-Ge (100) substrate was investigated. Experimental results indicated that Schottky barrier diodes on n-Ge (100) with current-voltage (I-V) rectifier characteristics were obtained. The I-on/I-off ratio of the Schottky diode obtained by using a 300° C annealing process is the highest. The Schottky barrier heights were evaluated by the capacitance-voltage method.