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Total-ionizing-dose (TID) effects are investigated in a highly-scaled gate-all-around (GAA) FET technology using Si nanowire channels with a diameter of 8 nm. n- and p-FETs are irradiated up to 300 Mrad(SiO2) and annealed at room temperature. TID effects are negligible up to 10 Mrad(SiO2). At ultrahigh doses, the TID degradation depends on the irradiation bias condition, with more severe effects observed in longer channel devices. The worst case irradiation condition is when positive bias is applied to the gate. Threshold-voltage shifts are caused by H+-driven generation of interface traps at the oxide/channel interface. In contrast, FETs irradiated under negative gate bias are dominated by transconductance loss and increases of low-frequency noise, suggesting the activation of border traps. Enhanced off-leakage current is observed in n-FETs due to charge trapping in shallow-trench isolation, and in p-FETs due to trap-assisted recombination at STI sidewalls and/or spacer dielectrics at drain/bulk junctions. [ABSTRACT FROM AUTHOR]

The energy distributions of electrons in gate-all-around (GAA) Si MOSFETs are analyzed using full-band 3-D Monte Carlo (MC) simulations. Excellent agreement is obtained with experimental current–voltage characteristics. For these 24-nm gate length devices, the electron distribution features a smeared energy peak with an extended tail. This extension of the tail results primarily from the Coulomb scattering within the channel. A fraction of electrons that enter the drain retains their energy, resulting in an out-of-equilibrium distribution in the drain region. The simulated density and average energy of the hot electrons correlate well with experimentally observed device degradation. We propose that the interaction of high-energy electrons with hydrogen-passivated phosphorus dopant complexes within the drain may provide an additional pathway for interface-trap formation in these devices. [ABSTRACT FROM AUTHOR]

We evaluate the total ionizing dose (TID) responses of InGaAs nMOS FinFETs with different gate lengths irradiated with 10-keV X-rays under different gate biases. The largest degradation after irradiation occurs at $V_{\mathrm {G}} = -1$ V. Radiation-induced trapped positive charge dominates the TID response of InGaAs FinFET transistors, consistent with previous results for InGaAs multifin capacitors. Shorter gate-length devices show larger radiation-induced charge trapping than longer gate-length devices, most likely due to the electrostatic effects of trapped charge in the surrounding SiO2 isolation and SiO2/Si3N4 spacer oxides. The 1/ $f$ noise measurements indicate a high trap density and a nonuniform defect-energy distribution, consistent with a strong variation of effective border-trap density with surface potential. [ABSTRACT FROM AUTHOR]

We have characterized the total ionizing dose response of strained Ge p MOS FinFETs built on bulk Si using a fin replacement process. Devices irradiated to 1.0 Mrad(SiO2) show minimal transconductance degradation (less than 5%), very small \text {V}_{th} shifts (less than 40 mV in magnitude) and very little ON/OFF current ratio degradation (<5%), and only modest variation in radiation response with transistor geometry (typically less than normal part-to-part variation). Both before and after irradiation, the performance of these strained Ge p$ MOS FinFETs is far superior to that of past generations of planar Ge $p$ MOS devices. These improved properties result from significant improvements in processing technology, as well as the enhanced gate control provided by the strained Ge FinFET technology. [ABSTRACT FROM PUBLISHER]

The total ionizing dose response of Ge channel pFETs with raised Si0.55Ge0.45 source/drain is investigated under different radiation bias conditions. Threshold-voltage shifts and transconductance degradation are noticeable only for negative-bias (on state) irradiation, and are mainly due to negative bias-temperature instability (NBTI). Nonmonotonic leakage changes during irradiation are observed, which are attributed to the competition of radiation-induced field transistor leakage and S/D junction leakage. [ABSTRACT FROM PUBLISHER]

Irradiated Ge pMOSFETs have been characterized via charge pumping (ICP) and 1/f noise. The noise increases much more with irradiation than does ICP for devices with eight Si monolayers at the interface, while devices with five Si monolayers and lower halo implantation dose exhibit comparable increases in noise and ICP with irradiation. These results suggest that border traps in the HfO2 affect the noise more than interface traps, and that devices with eight Si monolayers have a higher border-trap density than devices with five Si monolayers. Noise measurements as a function of gate voltage show that the border trap density increases significantly toward the Ge valence band edge, while three-level charge pumping reveals an interface trap density that increases slightly toward midgap. [ABSTRACT FROM AUTHOR]

The irradiation and annealing responses of Ge pMOSFETs have been investigated under transmission gate bias. Both the radiation-induced charge trapping and the low frequency (1/ f ) noise increase with total ionizing dose and decrease with annealing time. The smallest increases in noise after irradiation are observed for Ge pMOSFETs with the lowest halo implantation doses. The smallest increases in oxide and interface trap charge densities are obtained for devices with eight monolayers of Si at the interface, as compared to devices with five Si monolayers. [ABSTRACT FROM AUTHOR]