Abstract
A depletion‐mode field‐effect transistor is used to determine the electrical characteristics of a silicon‐on‐insulator (SOI) structure such as the Si film doping, the fixed oxide charges, and the interface trapped charges at the Si/SiO2 interfaces. We consider the case of a very thin Si film, i.e., the Si film thickness is smaller than the maximum depletion layer width. The electrical parameters of the SOI structure are derived from drain‐source current versus gate voltage and transconductance characteristics, provided that the back Si surface is accumulated by a proper substrate biasing. The device can be of small dimensions and can be used in process control without any extra process step.