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 tr ansistors (MOSFETs) by the random telegraph signals (RTSs) they induce by source-drain conductance modulations. The magnitude of the RTSs ob served frequently exceeds 10% of the channel conductance and it exhibi ts a large scatter over two orders of magnitude. Analytical estimates and computer modeling show that the magnitude of the RTSs and the scat ter cannot occur for a uniform MOSFET channel. It is concluded that fi xed oxide and interface charge centers, which are present in the activ e device area at a high concentration, cause a percolating current dis tribution in the channel. The lucky trap centers located close to curr ent 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 patter n. Trapping centers causing RTSs thus act as atomic probes of the nonu niform current distribution in the channel. (C) 1996 American Institut e of Physics.