On the origin of the 1/f noise in shallow germanium p(+)-n junctions

The low-frequency noise of shallow germanium p(+)-n junctions is studied, for diodes with or without a nickel-germanide Ohmic contact. It is shown that the application of NiGe not only reduces the series resistance, resulting in a higher forward current, but also results in a lower 1/f noise at forward bias. From the observed geometry dependence, it is concluded that germanidation suppresses the 1/f noise generated in the series resistance, leaving surface-state-assisted generation-recombination at the junction perimeter as the dominant flicker noise source