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A silicon-based field emission cathode, the rare earth silicide GdSi2 was prepared by implanting Gd ions into silicon using a metal vapor vacuum arc ion source and subsequently annealed by electron beam. For as-implanted samples, turn-on field was about 21V∕μm at a current density of 1μA∕cm2 and a field emission current density of 1mA∕cm2 was reached at an applied field of 34V∕μm. After annealing, the turn-on field could be as low as 9V∕μm and the current density of 1mA∕cm2 can be reached at an applied field of 14V∕μm. X-ray diffraction with x-ray photoelectron spectroscopy analyses and atomic force microscopy were used to characterize microstructure changes of the samples. The results showed that these excellent field emission characteristics were attributed to the GdSi2 compounds formed in the samples. The field emission mechanism was discussed in terms of Fowler-Nordheim (FN) theory. It was found that FN plots could be divided into two segments obviously, and this was perhaps because of the thermal effect in the process of field emission.

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