多晶键合层对分离吸收电荷倍增型锗/硅雪崩光电二极管性能的影响  

Effect of Different Polysilicon Bonding Layers Doping Concentration on Properties of Separated Absorption Charge Multiplication Ge/Si Avalanche Photodiodes

作　　者：苏小萍 李嘉辉 王战仁 柯少颖 SU Xiaoping;LI Jiahui;WANG Zhanren;KE Shaoying(College of Physics and Information Engineering,Minnan Normal University,Zhangzhou 363000,Fujian,China)

机构地区：[1]闽南师范大学物理与信息工程学院,福建漳州363000

出　　处：《硅酸盐学报》2024年第7期2316-2328,共13页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(62004087);福建省自然科学基金(2020J01815);漳州市自然科学基金(ZZ2020J32)。

摘　　要：分离吸收电荷倍增(SACM)型Ge/Si雪崩光电二极管(APD)因其高速、低噪声、高灵敏度、具备光增益等优点在光通信、光学成像和安全检测等领域具有广泛的应用前景。然而由于Si和Ge的晶格常数相差4.2%,因此在Ge/Si异质结界面会形成高密度的穿透位错,导致器件性能的恶化。为获得低位错密度Si基Ge薄膜材料并实现高性能Ge/Si APD,创新在Ge/Si键合界面处引入一层多晶硅(poly-Si)键合层弱化Ge/Si晶格失配对器件性能的影响,研究了poly-Si键合层掺杂浓度对键合Ge/Si APD性能的影响。研究表明,由于键合界面的晶格缓冲作用,键合Ge/Si APD在室温下可以获得极低的暗电流和较高的带宽,较低的poly-Si键合层掺杂浓度可获得性能较好的Ge/Si APD。该结果为提高Ge/Si APD的性能提供了理论依据。Introduction Ge/Si avalanche photodiode (APD) has attracted much attention in optical communication,optical imaging,and security detection due to its high-speed operation,low noise,high sensitivity,and optical gain characteristics.However,a mismatch between the lattice constants of Si and Ge (i.e.,a difference of 4.2%) has a challenge.This mismatch leads to a high density of threading dislocations at the Ge/Si heterojunction interface,ultimately deteriorating the performance of the device.Therefore,addressing the issue of lattice mismatch and reducing the dislocation density in Si-based Ge thin films is crucial for achieving high-performance Ge/Si APDs.To decrease the dislocation density of APDs,Si-based epitaxial Ge thin films are used as a fabrication method.However,the dislocation density continues to be relatively high.In this paper,the lattice mismatch between Ge and Si was alleviated.In addition,the theoretical underpinnings were also proposed.Methods In this research,a polycrystalline silicon (poly-Si) bonding layer was incorporated at the Ge/Si interface to mitigate the lattice mismatch effects.This poly-Si layer acted as a buffer,diminishing the stress and strain induced by the lattice mismatch.To assess the influence of the poly-Si bonding layer on the performance of Ge/Si APDs,a series of experiments at different doping concentrations of the poly-Si layer were carried out.The doping concentration was pivotal as it modulated the electrical and optical properties of the bonding layer,subsequently affecting the overall performance of the APD.The charge distribution,electric field distribution,and carrier transport within the Ge/Si APD device were delineated by the Poisson equation,carrier transport equation,carrier continuity equation,and a parallel electric field dependent model.This facilitated the computation of the device's electrical characteristics.The Ge/Si APD involved electron and hole recombination,the concentration-dependent SRH model was used to characterize the spontaneous emission and Auger

关 键 词：雪崩光电二极管 锗/硅键合 多晶硅键合层 晶格失配 键合层掺杂浓度 

分 类 号：TN315[电子电信—物理电子学]