Conductance modulation of submicrometer metal-oxide-semiconductor field-effect transistors by single-electron trapping

The capture and emission of electrons at single, individual interface traps is studied in sub-mu m metal-oxide-semiconductor field-effect transistors (MOSFETs) by the random telegraph signals (RTSs) they induce by source-drain conductance modulations. The magnitude of the RTSs observed frequently exceeds 10% of the channel conductance and it exhibits a large scatter over two orders of magnitude. Analytical estimates and computer modeling show that the magnitude of the RTSs and the scatter cannot occur for a uniform MOSFET channel. It is concluded that fixed oxide and interface charge centers, which are present in the active device area at a high concentration, cause a percolating current distribution in the channel. The lucky trap centers located close to current paths give rise to large RTSs. The scatter in the magnitude of the RTSs is due to the random location of traps in the percolation pattern. Trapping centers causing RTSs thus act as atomic probes of the nonuniform current distribution in the channel. (C) 1996 American Institute of Physics.