In this work, parametric investigations on structural optimization are systematically made for 4H-SiC-based separated absorption charge and multiplication (SACM) avalanche ultraviolet photodiode (UV APD). According to our results, the breakdown voltage can be strongly affected by the thickness for the multiplication layer and the doping concentration for the charge control layer. The thickness for the n-type ohmic contact layer, the absorption layer, and the charge control layer can remarkably affect the light penetration depth, which correspondingly influences the number of photo-generated electron-hole pairs, and therefore the aforementioned layer thickness has a strong impact on the responsivity for SACM APD. For enhancing the responsivity of the APD, we require a reduced energy band barrier height at the interface of the optical absorption layer and the charge control layer, so that the promoted carrier transport into the multiplication layer can be favored. In addition, we investigate positive beveled mesas with smaller angles so as to reduce the electric field at the mesa edge. Thus, the dark current is correspondingly suppressed.

中文翻译：

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高紫外线检测效率的4H-SiC分离吸收电荷和倍增雪崩光电二极管结构的优化策略。

在这项工作中，系统地对基于4H-SiC的分离吸收电荷和倍增（SACM）雪崩紫外光电二极管（UV APD）进行了结构优化的参数研究。根据我们的结果，击穿电压会受到乘法层厚度和电荷控制层掺杂浓度的强烈影响。n型欧姆接触层，吸收层和电荷控制层的厚度会显着影响光穿透深度，从而相应地影响光生电子-空穴对的数量，因此上述层厚度为强烈影响SACM APD的响应度。为了增强APD的响应能力，我们要求在光吸收层和电荷控制层的界面处减小能带势垒高度，以便促进载流子向倍增层的迁移。另外，我们研究了具有较小角度的正斜面台面，以减小台面边缘处的电场。因此，暗电流被相应地抑制。