Turn-Around Effect of Shift During the Positive Bias Temperature Instability of the n-Type Transistor With Gate Dielectrics

This letter examines the turn-around effect of a threshold voltage (V_th) shift of an n-type transistor with atomic-layer-deposited HfO_xN_y gate dielectrics under a positive gate bias. V_th shifted to the positive voltage direction during the first second due to electron trapping at the preexisting trap sites in the gate dielectrics, which then shifted to the negative voltage direction. This turn-around effect was attributed to hole trapping originating from the generation of electron-hole pairs by the surface plasmon or impact ionization.