Low-frequency noise as a tool for characterization of near-band impurities in silicon

Abstract Low-frequency noise vs temperature characterization of energy levels in the Si bandgap has been extended down to 6 K for both N- and PMOSFETs. These energy levels, acting as generation-recombination centers, cause peaks in the noise vs temperature scan of the MOSFET, from which estimates of the trapping parameters (energy and capture cross-section) of these levels may be obtained. Such low temperatures, not previously investigated by this method, allow observation of energy levels very close (20–40 meV) to the valence or conduction band. Such levels were observed in every one of a wide range of processes tested. The possible origins of such near-band levels are discussed.