Numerical simulation of avalanche hot-carrier injection in short-channel MOSFET´s

Based on two-dimensional MOSFET simulation, the substrate and gate currents resulting from impact ionization generated electron-hole pairs and their injection into the gate oxide are calculated. The improved injection model uses a nonMaxwellian distribution function and considers separate contributions to the gate current from both thermionic-emission and oxide-barrier tunneling. A fine structure in experimentally observed I_g^e vs. v_g curves for thin-oxide devices at v_g approximately=2.3v_d is simulated. Simulation of a lightly doped drain (LDD) MOSFET also reveals the unusual feature of a double hump in the substrate current and an abrupt increase of the gate current beginning at v_g approximately=3/2v_d.