Hall effect, anisotropy, and temperature-dependence measurements of 1/f noise in silicon on sapphire

Measurements of several properties of 1/f noise in n-type silicon-on-sapphire wafers were made in the temperature range 100-330 K. The resistance fluctuations were nearly scalar, independent of temperature. The magnitude of the Hall-effect noise was larger than that predicted for simple carrier-number fluctuations at 100 and 140 K, but less at 300 K. The correlation between the Hall fluctuations and resistivity fluctuations had the same sign and slightly lower magnitude than would be expected for majority-carrier number fluctuations. Temperature-dependent features in the spectrum showed that the kinetics were thermally activated, while the weak temperature dependence of the magnitude of the features showed that the activated process could not be a simple electronic transition alone. A model involving slow processes at lattice defects modulating the depth of traps is suggested, and similarities and contrasts with other materials are discussed.