The Origin of the Anomalous Off-current in SOI-Transistors

The leakage currents exhibited by silicon-on-insulator (SOI) transistors show a strong dependence on gate and drain voltage. Measurements on lateral p
⁺
-n junction diodes fabricated using separation by implanted oxide (SIMOX) technology suggest that reverse leakage currents originate from field enhanced generation in the depletion region. A model is presented which supports this process. In SOI-transistors field intensification occurs in the drain depletion region for increasing drain voltage and increasing gate voltage in the ``off'' direction. This mechanism can therefore explain the strong dependence of leakage currents on terminal voltage.