Effect of tungsten coating on the properties of high-resistivity gold-doped silicon

We have studied the effect of tungsten atoms (tungsten coating) on the properties of gold-doped silicon. The coating considerably increased the resistivity of the silicon and markedly reduced the photoconductivity relaxation time. The silicon doped with gold in the presence of tungsten was found to have an energy level with an ionization energy E = E _c ? (0.23 ± 0.02) eV. In uncoated gold-doped silicon, no energy level with such ionization energy was found. This strongly suggests that the energy level with an ionization energy E = E _c ? (0.23 ± 0.02) eV is due to tungsten centers.