An extraordinary kink phenomenon in static back-gate transconductance characteristics of fully-depleted SOI MOSFET's has been experimentally investigated and characterized for the first time. This kink phenomenon has been observed in both NMOS and PMOS on high-dose SIMOX wafers under steady-state conditions at room temperature. It was also found that the back-gate characteristics for both NMOS and PMOS show anomalous shift phenomenon in drain current-back gate voltage (ID-DG2) curve at the back-gate voltage corresponding to the kink phenomenon. This kink phenomenon has been attributed to the presence of energetically-localized trap states at SOI/BOX interface. In order to clarify the energy level of the trap states at SOI/BOX interface corresponding to the kink, we have developed a new formula of surface potential in thin-film SOI MOS devices, in which the potential drop across semiconductor-substrate is taken into account. By using this new formula, we have demonstrated that high-dose SIMOX wafers have the donor-like electron trap states at approximately 0.33 eV above the Si midgap with the density of approximately 6.0×1012 cm-2 eV-1 and the donor-like hole trap states at approximately 0.35 eV below the Si midgap with the density of approximately 1.5×1012 cm-2 eV-1 at SOI/BOX interface.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering