Schottky barrier characteristics of polycrystalline and epitaxial CoSi2/n-Si (111) contacts formed by solid state reaction

Polycrystalline and epitaxial CoSi2 films were formed on the n-Si (111) substrates by solid state reaction of the as-deposited Co single-layer and Co/Ti bilayer with Si respectively at different annealing phase. The CoSi2/Si Schottky contacts were measured with the current-voltage and capacitance-voltage (I-V/C-V) techniques within the temperature range from 90 K to room temperature. The I-V characteristics were analyzed with a model based on the inhomogeneity in Schottky barrier height at high temperatures (≥200 K) or low temperatures with a large bias, and the I-V curves were described by the thermionic emission theory with a Gaussian distributed barrier height over the whole junction, while at low temperatures with a small bias, the current was dominated by some small patches with low barrier height. It results in a plateau-like section in the low temperature I-V curves around 10-7 A. At room temperature, the barrier height of polycrystalline CoSi2/Si deduced from the I-V curve is about 0.57 eV. For epitaxial CoSi2, the barrier height depends on its final annealing temperature and increases from 0.54 eV to 0.60 eV with the annealing temperature increasing from 700°C to 900°C.