Analytical modeling of surface accumulation behavior of fully depleted SOI four gate transistors (G4-FETs)

A charge sheet model is proposed to analyze the transistor characteristics of fully depleted SOI four gate field effect transistors (G4-FETs). The model is derived assuming a parabolic potential variation between the junction-gates and by solving 2-D Poisson’s equation. The proposed model facilitates the calculation of surface potential and charge densities as a function of all gate biases. Modifying this charge sheet model for non-equilibrium condition, current–voltage and capacitance–voltage characteristics are also analyzed. Different back surface charge conditions are considered for each analysis. The models are compared with 3-D Silvaco/Atlas simulation results which show good agreement.

► A charge sheet model is derived by analytically solving 2-D Poisson’s equation.
► First analytical model for FD G4-FET above threshold condition.
► Models for drain current and gate capacitance are also proposed.
► Good tools for designers because of low computational time and good accuracy.
► Good accuracy with Atlas/Silvaco 3D devices simulation.