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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 report the experimental data, quantum-mechanical calculations, and engineering-level modeling that provide insight into the atomic-scale processes that underlie the hot-electron degradation of AlGaN/GaN high-electron-mobility transistors during electrical stress at moderate drain bias. There is relatively large degradation (up to 20%) of the peak transconductance ( gm ) in the semi-ON state, along with a small shift of the threshold voltage ( VT ). The VT shift and gm degradation increase with temperature. A model of the degradation is presented, based on the hot-carrier-induced defect generation. The model considers carrier energy distributions for different temperatures obtained using an ensemble Monte Carlo (EMC) approach. The Ensemble Monte-Carlo results show that the concentration of energetic carriers is maximum at the end of the gate on the gate–drain access side in the semi-ON state of operation. The degradation is directly related to the number of carriers with sufficient energy to generate defects, and the carrier energy distribution depends strongly on the device temperature. The first-principles density functional theory calculations and the analysis suggest that the dehydrogenation of substitutional iron and its complexes is the dominant cause of the observed degradation in these devices. [ABSTRACT FROM AUTHOR]

The temperature dependence of the low-frequency noise of 4H-silicon carbide (SiC) MOSFETs with nitrided oxides is reported over the temperature range 85–510 K. The 1/f noise decreases significantly with increasing measurement temperature. This decrease in noise results primarily from a decrease in the density of interface traps at increasing temperatures. The 1/f noise is also characterized after total ionizing dose irradiation and postirradiation annealing. No significant change in the 1/f noise is observed after the devices are irradiated to 1 Mrad (SiO2) and then annealed under bias at elevated temperature. These results show that the 1/f noise in 4H-SiC MOSFETs is dominated by the interaction of channel carriers with slow interface traps at temperatures <360~K and with border traps >\rm\!360~K. This result contrasts with most experience with Si/SiO2-based MOSFETs, and results from the wider bandgap and greater density of slow interface traps in SiC/SiO2-based MOSFETs than in Si/SiO2-based MOSFETs. [ABSTRACT FROM AUTHOR]