Unified analytic model of direct and Fowler-Nordheim tunnel currents through ultrathin gate oxides

A theoretical model to predict the gate tunnel current in metal-oxide-semic onductor structures has been developed by employing the nonparabolic E-k di spersion for describing the tunneling electron momentum. The tunnel electro n effective mass m(ox) and the Fermi energy in the gate have been used to f it the calculated tunnel current to the measured one. It is shown that in t he direct tunneling regime the tunnel electron effective mass m(ox) apparen tly increases with decreasing oxide thickness presumably due to the reducti on of Si-O-Si bond angle in the compressively strained layer near the SiO2/ Si interface, while in the Fowler-Nordheim tunneling regime m(ox) remains c onstant at 0.50 m(0). (C) 2000 American Institute of Physics. [S0003-6951(0 0)03249-6].