—We constructed a model for a 3-stage InGaAs/InAlAs avalanche photodiode using numerical simulations based on the gain-noise mechanism. The contact layer, barrier layer, charge layer and multiplication layer of this model are optimized accordingly. The performance of the device can be improved by optimizing the thickness and doping concentration of the contact layer, increasing the thickness of the charge layer, and adding a barrier layer. At the same time, the addition of double heterojunction structure makes the performance of the device better, which enables a higher impact ionization rate of the multiplication layer. According to DSMT theory calculation results, the optimized 3-gain-stage device's gain is 90, and the excess noise factor is about 3.1. Compared with the 10-stage avalanche photodiode (with an excess noise factor of 5) studied at the same gain, this work shows higher performance at the lower stage. The optimized structure can provide design and optimization ideas for more stages of avalanche photodiode to increase gain and reduce excess noise.

中文翻译：

---

三增益级 InGaAs/InAlAs 雪崩光电探测器的增益和过量噪声特性

—我们使用基于增益噪声机制的数值模拟构建了 3 级 InGaAs/InAlAs 雪崩光电二极管的模型。该模型的接触层、势垒层、电荷层和倍增层都进行了相应的优化。通过优化接触层的厚度和掺杂浓度、增加电荷层的厚度、添加势垒层等可以提高器件的性能。同时，双异质结结构的加入使得器件的性能更加出色，使得倍增层具有更高的碰撞电离率。根据DSMT理论计算结果，优化后的三增益级器件增益为90，过量噪声系数约为3.1。与相同增益下研究的10级雪崩光电二极管（过量噪声系数为5）相比，这项工作在较低级表现出更高的性能。优化后的结构可以为更多级雪崩光电二极管提供设计和优化思路，以提高增益并减少多余噪声。