Modeling of anomalous current-voltage characteristics in floating body fully depleted SOI nMOSFETs

Abstract

An analytic model is derived for predicting the anomalous I D− V GfS and I D− V DS characteristics in a floating body fully depleted silicon-on-insulator (SOI) nMOSFETs with parasitic bipolar junction transistor (BJT). All current components in the MOSFET as well as the parasitic BJT are considered in this model. It shows that the single-transistor latch in the I D− V GfS characteristics is due to multistable floating body potentials. The study also reveals that the breakdown and latch phenomena are strongly dependent on the parasitic bipolar current gain and multiplication factor. The effective mobility variation and short channel effects are included in this model. Furthermore parametric dependences, such as SOI film thickness and body doping concentration, are examined to alleviate the latch effect and give the physical insight for optimal design. Results obtained from this model are in good agreement with the measured I D− V GfS and I D− V DS characteristics.