LOW-TEMPERATURE CONDUCTIVITY OF ULTRA THIN DEPOSITS OF AG ON GE(100)

We present low temperature conductivity data on ultra thin (d < 25 angstrom) Ag layers grown on Ge(001)2x1 substrates under UHV conditions. Samples grown at 160K and subsequently annealed at room temperature appear to have an intermediate layer plus islands structure. The islands are elongated in one of two normal directions. After air exposure, these samples show a maximum in their electrical resistance at about 8 K and a minimum around 5 K. The current and magnetic field dependence of the resistance between 8K and 0.7K is consistent with an incomplete superconducting transition. Although all samples show an increase in overall resistance with time after air exposure, the transition temperature remains fairly constant. The increase in resistance below 5K is ascribed to normal regions within the intermediate layer.