In this work, a new model for the mobility due to Coulombic scattering by interface charges ( μ C) in 4H-SiC MOS structures, which is suitable for device study via finite element (FE)-based simulations, is proposed. Unlike popular expressions based on the classical Sah–Lombardi model which lead to major inconsistencies in μ C’s variation with the semiconductor depth z, the proposed model combines previous experimental data with established theoretical results on μ C’s depth dependence. The evolution of the components of the channel drift mobility ( μ c h) with z and the gate bias V g s is then examined using this model by means of FE analysis. It is found that while μ C is the dominant component at the surface, at larger depths μ c h is determined by the mobility due to acoustic phonon scattering ( μ S A). Moreover, at low channel dopings ( N A) or temperatures above approximately 425 K , μ S A replaces μ C as the key limitation. Conversely, the roughness scattering mobility μ S R becomes important only at very high V g s and N A.

中文翻译：

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4H-SiC 反型层中库仑散射迁移率的高级物理模型

在这项工作中，提出了一种由 4H-SiC MOS 结构中界面电荷 (μC) 引起的库仑散射引起的迁移率的新模型，该模型适用于通过基于有限元 (FE) 的模拟进行器件研究。与基于经典 Sah-Lombardi 模型的流行表达式不同，该模型导致 μ C 随半导体深度 z 的变化存在重大不一致，所提出的模型将先前的实验数据与已建立的关于 μ C 深度依赖性的理论结果相结合。然后使用该模型通过有限元分析检查沟道漂移迁移率 (μ ch) 的分量随 z 和栅极偏置 V gs 的演变。发现虽然μ C 是表面的主要成分，但在较大深度处，μ ch 由声子散射（μ SA）引起的迁移率决定。而且，在低沟道掺杂 (NA) 或高于大约 425 K 的温度下，μ SA 取代 μ C 作为关键限制。相反，粗糙度散射迁移率 μ SR 只有在非常高的 V gs 和 N A 时才变得重要。