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Assessment of Self-Heating Effects Under Lateral Scaling of GaN HEMTs
摘要： The impact on self-heating mechanisms observed in GaN HEMTs fabricated on Si substrates is studied by means of a cellular Monte Carlo particle-based device simulator. Within this framework, the thermal effects are included through an energy-balance equation for phonons allowing for self-consistently coupling the charge and heat transport. First, the advanced electrothermal model of an experimental device is developed and calibrated to measured dc characteristics, showing an accurate description throughout the IDS(VGS?VDS) space, as a result of capturing the temperature dependence of the scattering processes that modify the charge transport. Then, the model is used to assess the effect of lateral scaling, i.e., reducing the source-to-gate LSG and gate-to-drain LGD dimensions, in terms of detailed temperature maps obtained for the acoustic and optical phonon modes as well as the electric field and carrier velocity profiles. It is found that the hot spot in the channel is not located at the peak electric field as predicted by previous methods, but instead, it is shifted toward the drain up to 32 nm. Furthermore, it is shown that, while scaled devices offer improved dc and small-signal ac performance, they are subjected to temperatures up to 15% higher in the channel as compared to the original nonscaled device when dissipating the same dc power, and the temperature distribution throughout the device shows a strong correlation with the scaled layout.
关键词： reliability,HEMTs,Monte Carlo methods,self-heating,scaling,GaN
更新于2025-09-23 15:22:29
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Two-dimensional projection Monte Carlo estimators for the study of angular characteristics of polarized radiation
摘要： The paper presents a Monte Carlo algorithm for the study of bidirectional angular characteristics of a scattered polarized radiation based on projection expansion of the density of the corresponding angular distribution over hemispherical harmonics. The results of numerical estimation of two-dimensional angular distributions of the intensity and the polarization degree of the radiation passed through and reflected from optically thick layers of scattering and absorbing substance are presented.
关键词： statistical modelling,radiation transfer,Monte Carlo methods,orthogonal expansion,hemispherical harmonics
更新于2025-09-11 14:15:04