The influence of space quantization effects on the threshold voltage, inversion layer and total gate capacitances in scaled Si-MOSFETs

We investigate the influence of space quantization and poly-gate depletion on the inversion layer capacitance C_inv, total gate capacitance C_tot and threshold voltage V_T in scaled Si-MOSFETs. We also present an analytical expression for the total gate capacitance C_tot that uses classical charge description and takes into account the depletion of the poly-silicon gates. Our simulation results suggest that poly-gate depletion influences the magnitude of C_tot more than the quantum mechanical charge description. For the threshold voltage V_T the situation is more complicated; it is significantly affected by both the poly-gate depletion and the quantum effects in the channel.