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Hot-carrier degradation is associated with the buildup of defects at or near the silicon/silicon dioxide interfaced of a metal-oxide-semiconductor transistor. However, the exact location of the defects, as well as their temporal buildup during stress, is rarely studied. In this work we directly compare the experimental interface state density profiles generated during hot-carrier stress with simulation results obtained by a hot-carrier degradation model. The developed model tries to capture the physical picture behind hot-carrier degradation in as much detail as feasible. The simulation framework includes a transport module, a module describing the microscopic mechanisms of defect generation, and a module responsible for the simulation of degraded devices. Due to the model complexity it is very important to perform a thorough check of the output data of each module before it is used as the input for the next module. In this context a comparison of the experimental interface state concentration observed by the charge-pumping technique with the simulated one is of great importance. Obtained results not only show a good agreement between experiment and theory but also allow us to draw some important conclusions. First, we demonstrate that the multiple-particle mechanism of Si–H bond breakage plays a significant role even in the case of a high-voltage device. Second, the absence of the lateral shift of the charge-pumping signal means that no bulk oxide charge buildup occurs. Finally, the peak of interface state density corresponds to the peak of the carrier acceleration integral and is markedly shifted from typical markers such as the maximum of the electric field or the carrier temperature. This is because the degradation is controlled by the carrier distribution function and simplified schemes of hot-carrier treatment (based on the mentioned quantities) fail to describe the matter.

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The multicaloric effect that is the result of interaction between various caloric effects has been studied theoretically. The effects attributable to the pairwise interactions of fields (piezomagnetocaloric, piezoelectrocaloric, and magnetoelectrocaloric effects) have been added to the previously known electroca loric, magnetocaloric, and elastocaloric effects that exist when the electric, magnetic, and elastic fields change. These new effects are shown to be determined by the temperature dependence of the piezomagnetic (magnetostrictive), piezoelectric (electrostrictive), and magnetoelectric coefficients. According to the esti mates obtained, the change in entropy in an isothermal process under the magnetoelectrocaloric effect for Cr 2 O 3 is 2-5 mJ kg -1 K -1 . The caloric effects caused by the influence of the gradient in one of the fields on other fields are shown to contribute to the multicaloric effect. One of these gradient effects, the flexocaloric one, which consists in a change in temperature and/or entropy when a strain gradient is applied or removed, has been studied in detail as an example. It follows from the derived formulas that the greatest values of this effect should be expected for materials with strong temperature dependences of the flexocaloric coefficient, permittivity, or permeability. The change in temperature calculated from experimental data for a PMN fer roelectric is estimated as 2-6 mK at a strain gradient of 1 m -1 . The interaction between fields of a different nature is known to lead to the synergetic effect, and the multicaloric effect can reach values that are com monly called giant ones, expanding considerably the possible domains of its application.

We present and verify a physics-based model of hot-carrier degradation (HCD). This model is based on a thorough solution of the Boltzmann transport equation. Such a solution can be achieved using either a stochastic solver based on the Monte Carlo approach or a deterministic counterpart that is based on representation of the carrier energy distribution function as a series of spherical harmonics. We discuss and check two implementations of our model based on these methods. The model is verified vs. the HCD experimental data measured in longchannel transistors as well as in ultra-scaled MOSFETs. Because both stochastic and deterministic methods have advantages and shortcomings, we study the limits of applicability of these methods. We aim to cover and link all main features of HCD, namely, the interplay between hot and colder carriers, which leads to two competing mechanisms of bond breakage and the strong localization of hot-carrier damage. Our model is linked and compared with other approaches to HCD simulations. Special attention is paid to the importance of the particular model ingredients, such as competing mechanisms of the Si-H bond dissociation, electron-electron scattering, variations in the bond-breakage energy, as well as its reduction due to the interaction between the dipole moment of the bond and the electric field. We also analyze the role of electron-electron scattering in HCD measured in devices with different gate lengths.

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