Why is oxide-trap charge-pumping (OTCP) method appropriate for extracting the radiation-induced traps in mosfet?

Oxide-trap charge-pumping (OTCP) method is used to estimate radiation-induced oxide-, interface-, and border-traps in complementary N- and P-MOS transistors. We conduct a critical comparison between OTCP and classical methods like subthreshold slope (STS), mid gap (MG), dual-transistor charge-pumping (DTCP), and dual-transistor border-trap (DTBT). On the one hand, OTCP offers more accurate densities of radiation-induced interface-traps (DeltaN_it) and border-traps (DeltaN_bt), while STS and MG overestimate DeltaN_it because both interface- and border-trap are sensed like interface-traps. On the other hand, OTCP estimates DeltaN_it, DeltaN_bt, and radiation-induced oxide-trapped positive charge (DeltaN_ot) for N- and P-MOS separately, whereas DTCP and DTBT give average densities for both devices.