Anomalous subthreshold slopes in thin-film accumulation-mode SOI p-channel MOSFET´s

The authors report the observation of anomalously sharp (<60 mV/dec) subthreshold slopes in accumulation-mode p-channel MOSFETs on ultrathin SOI films. Despite the different current flow mechanism, the subthreshold slope in accumulation-mode p-channel devices shows a similar substrate bias dependence to that of inversion-mode n-channel devices. Impact ionization near the drain region and electron trapping at the backside interface in the case of a large substrate bias are the main factors for the wide range of subthreshold slopes. Anomalously sharp subthreshold slopes can be avoided by control of the lower SOI interface charge condition