Semiconductors produced by doped oxide-glasses with Ir, Pd, Rh or Ru

Abstract

Semiconductors have been produced by diffusion doping of oxide glasses with more than 1 wt% of Ir, Pd, Rh or Ru and by implanting 40 kV Ir ions into several oxide glasses. The Hall mobility at 300°K and 78°K is less than 0.005 cm 2/V sec. The mobility deduced from the impurity concentration and the conductivity is 0.001 cm 2/V sec. The conductivity is not ionic; enough direct current was passed through one sample to have plated out a million times as many Ir ions as were in the sample with no change in conductivity. X-ray small angle scattering indicated that the conductivity is not due to electron hopping between conducting islands. The conductivity is ohmic at 300°K and is field dependent below 4°K. The thermoelectric power of 12 to 25 μV/deg relative to copper indicates hole conduction. The material absorbs throughout the visible region. If the firing temperature and time at a constant oxygen pressure are kept constant, the conductivity increases as the impurity concentration increases and varies from 10 −3 to 10 2 reciprocal ohm-cm. For a constant concentration of platinum-metal ions and for equilibrium firing, the conductivity is directly proportional to the oxygen pressure. Firing in hydrogen to remove oxygen reduces conductivity at the rate of two carriers per oxygen atom removed. These data indicate that the frozen-in valence states of the platinum-metal ions serve as the source of the carriers.