Analytical model for deriving the threshold voltage of a short gate SOI MESFET with vertically non-uniformly doped silicon film

An analytical model for deriving the threshold voltage of a short gate SOI MESFET in which the silicon film doping density is vertically non-uniform is suggested. Taking into account the lateral variation of the bottom channel potential and using the derived natural length expression, the potentials in both silicon film and buried oxide layer are derived fully two-dimensionally. Making use of them, the minimum bottom channel potential can be obtained to describe the threshold voltage expression in terms of device parameters and applied voltages. Obtained results can be found to explain the drain-induced barrier lowering, drain-induced threshold voltage roll-off and the back-gate effect in a unified manner.