Gated-diode characterization of the back-channel interface on irradiated SOI wafers

A silicon-on-insulator (SOI) MOSFET-based "gated-diode" technique has been applied to study the Si-film/buried-oxide interface of devices that were fabricated on a SIMOX wafer. Since the gated-diode technique is sensitive to recombination current caused by the presence of interface states, the samples were exposed to 10 keV X-ray irradiation to enhance the development of SOI back-channel interface states. The measured peak in the gated-diode current curve was observed to increase in magnitude and move in voltage as a function of exposure to radiation in a manner consistent with increasing interface states and increasing trapped oxide charge. Using a two-dimensional numerical simulator, with a single acceptor interface trap at 0.7 eV, the gated-diode current was modeled as a function of 10 keV X-ray exposure.