ANALYTICAL STUDY OF THE CONTRIBUTION OF FAST AND SLOW OXIDE TRAPS TO THE CHARGE-PUMPING CURRENT IN MOS STRUCTURES

An analytical expression of the charge pumping (CP) current in a MOS d evice is derived for fast and slow interface traps, after assuming sho rt gate bias transition times and neglecting the emission of carriers. In the case of fast interface traps, this simple CP formulation enabl es a good description of the charge pumping characteristics for genera l purpose CP configurations. It is used to demonstrate the influence o f the doping concentration on the CP characteristics. It is also shown that the slow oxide traps induce a recombination current which can be of the same order of magnitude compared to that due to the fast inter face traps. The characteristics of this current are discussed in terms of the trap parameters. In the case of a continuum of volume oxide tr aps, the apparent interface trap density, which is measured in the con ventional CP technique, is also investigated and discussed for state-o f-the-art MOS structures.