Unraveling the Dynamics of Charge Trapping and De-Trapping in Ferroelectric FETs

Abstract

In this work, a comprehensive study of charge trapping and de-trapping dynamics is performed on n-channel ferroelectric field-effect transistors (nFeFETs) and pFeFETs. It is discovered that: 1) the degree of charge trapping depends on the substrate that nFeFETs exhibit significant electron trapping but negligible hole trapping during memory write while pFeFETs exhibit much less electron trapping but significant hole trapping when heavily stressed; 2) due to enhanced electric field in the interlayer and semiconductor, the like initial polarization states (i.e., initialized by a pulse of the same polarity as the write pulse) could exacerbate charge trapping induced by the write pulse; 3) electron trapping is fully recoverable while hole trapping shows a semi-permanent component which involves interface trap generation; and 4) less significant charge trapping in pFeFETs allows immediate read-after-write at normal operating conditions.