重点研究了多级倍增超晶格InGaAs雪崩光电二级管(APD)的增益和过剩噪声, 建立了新的载流子增益-过剩噪声模型。在常规弛豫空间理论基础上分析了其工作原理, 考虑了预加热电场和能带阶跃带来的初始能量效应、电子进入高场倍增区时异质结边界附近的弛豫空间长度修正以及声子散射对碰撞离化系数的影响, 提出了用于指导该类APD的增益-过剩噪声计算的修正弛豫空间理论。结果表明: 在相同条件下, 相比于常规的单层倍增SAGCM结构, 多级倍增超晶格InGaAs APD同时具有更高增益和更低噪声, 且修正的弛豫空间理论可被推广到更多级倍增的超晶格InGaAs APD结构, 在保证低噪声前提下, 通过增加倍增级数可提高增益。

The gain and excess noise of multi-gain-stage superlattice InGaAs APD was mainly studied in this paper, and a new multiplication-excess noise model of carriers was established. Based on the conventional Dead Space Multiplication Theory, we analyzed its working principle. Additionally, we considered initial energy from pre-heat electric field and energy band offset, and the modification of dead space length around heterojunction′s boundary when carriers entered high-field multiplication layer, as well as the effect of phonon scattering on impact ionization coefficients. Thus we proposed a modified Dead Space Multiplication Theory to guide the calculation of the gain and excess noise factor of this type of APD device. The results demonstrated that under the same condition, multi-gain-stage superlattice InGaAs APD has both higher gain and lower noise than conventional SAGCM APD with a single multiplication layer, and the modified Dead Space Multiplication Theory can be extended to superlattice InGaAs APD structure with more gain stages. On the premise of low excess noise, its mean gain can be improved by increasing number of gain stages.