Origin of noise in two dimensionally doped silicon and germanium

Abstract

We present the study of low-frequency noise, or 1/f noise, in degenerately doped Si:P and Ge:P δ-layers at low temperatures. For the Si:P δ-layers we find that the noise is several orders of magnitude lower than that of bulk Si:P systems in the metallic regime and is one of the lowest values reported for doped semiconductors. Ge:P δ-layers as a function of perpendicular magnetic field, shows a factor of two reduction in noise magnitude at the scale of Bφ, where Bφ is phase breaking field. We show that this is a characteristic feature of universal conductance fluctuations.