Back and front interface related generation-recombination noise in buried-channel SOI pMOSFETs

This paper reports on a detailed study of generation-recombination (GR) noise in buried-channel silicon-on-insulator (SOI) pMOSFETs, occurring in the linear operation mode. In particular, the plateau amplitude and the corner frequency (relaxation time τ) of the Lorentzian are investigated as a function of the front (V_Gf) and of the back gate bias (V_Gb). It is shown that different cases can be distinguished, depending of the conduction mode of the device, i.e. for surface or buried channel operation. For surface channel operation the GR noise parameters are strongly influenced by the back gate bias and only weakly dependent on V_Gf. The opposite is true when the front interface starts to deplete, thereby pushing the channel deeper into the Si film. As is shown, the relaxation time depends exponentially on either V_Gf or V_Gb. A similar exponential gate-bias dependence is found for the Lorentzian amplitude. Based on the observations, it is concluded that the GR noise originates from the front or the back interface, depending on the operation mode. The effective density of front and back interface traps can be derived from the GR noise amplitude