Ch31（3/3）：压电与力学求解器

Sentaurus Device 提供了两个模型（应变和应力）来计算 GaN 器件中的极化效应。它们可以在命令文件的 Physics 部分中激活：

Physics {
    Piezoelectric_Polarization (strain)
    Piezoelectric_Polarization (stress)
}

应变模型

压电极化矢量 可以表示为局部应变张量 的函数：

其中 是自发极化矢量 [C/cm²]， 是应变-电荷压电系数 [C/cm²]。

应力模型

应力模型计算完整极化矢量（张量形式），不做简化假设：

其中 是压电系数 [cm/V]， 是应力张量 [Pa]。

基于极化矢量，压电电荷根据下式计算：

该值被添加到泊松方程的右边。

力学求解器

NOTE

Sentaurus Device 中的力学求解器是一个实验性功能，在未来版本中可能会被修改。

在器件仿真过程中，应力张量可能作为解变量的函数而变化。例如：

• 不同材料具有不同的热膨胀系数。这种热失配导致应力随器件晶格温度变化而变化。
• GaN HEMT 的电退化提出由于与逆压电效应相关的过度应力形成缺陷。在这种情况下，应力张量随局部电场变化。

Sentaurus Device 在 Solve 部分提供了 Mechanics 语句，以响应偏置条件的变化重新计算应力张量。

Sentaurus Device 依赖 Sentaurus Interconnect 来更新应力张量。Solve 部分中的 Mechanics 语句执行以下操作：

• Sentaurus Device 创建一个包含当前解变量（如静电势 或晶格温度 ）的输入结构（TDR 文件）以及 Sentaurus Interconnect 命令文件。
• Sentaurus Device 调用 Sentaurus Interconnect。
• Sentaurus Interconnect 更新机械应力并产生输出 TDR 文件。
• Sentaurus Device 读取 Sentaurus Interconnect 生成的 TDR 文件并更新应力张量。

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