Comparison of amorphous Mo and Cr disilicides in hydrogenated amorphous silicon

The general features of Mo and Cr disilicides formed in hydrogenated amorphous silicon (a-Si:H) have been compared. Following deposition of the chromium and molybdenum films at room temperature the films were annealed over a range of times and temperatures below 350°C. It was found that in both cases stable metal disilicides were formed at the interface of a-Si:H with the metals. TEM measurements confirmed that the silicides were amorphous. In both cases the amorphous silicide was only a few nanometers thick with the square of the thickness proportional to the annealing time. In the case of Mo a much thinner silicide layer was formed. The density derived from the thickness and metal surface density was close to the value for crystalline CrSi2 and MoSi2 for all films formed in the range of temperatures used. The activation energies for the formation process for CrSi2 and MoSi2 were ≈0.55 eV and ≈0.4 eV and their specific resistivities were ≈600 μΩ cm and ≈1000 μΩ cm, respectively.