通过直接GeSn集成将硅雪崩光电探测扩展至2μm以上
Extending Silicon Avalanche Photodetection Beyond $2~μ$m by Direct GeSn Integration
AI总结：
本研究通过直接无缓冲层生长GeSn于硅衬底，结合横向薄结分离吸收-倍增架构，实现了可扩展的硅雪崩光电探测光谱范围扩展，制备的器件具备优异性能，适用于多领域单片红外探测器开发。
AI中文摘要：
硅雪崩光电二极管是技术成熟的高灵敏光电探测平台，但其光谱响应受硅带隙的固有限制。要将其工作范围扩展至红外波段，需集成窄带隙吸收层，同时保持高效的雪崩倍增特性及与硅工艺的兼容性。本研究提出并验证了一种单片集成方案：将GeSn直接无缓冲层生长于硅衬底，结合横向薄结分离吸收-倍增架构。该GeSn层的锡（Sn）组分为6 at.%，可将光吸收范围扩展至2.6μm；雪崩倍增则空间上限定于离子注入形成的硅横向结。这种分离设计可独立调控红外吸收与载流子倍增，无需GeSn外延常用的厚Ge虚拟衬底。所制备的GeSn-on-Si雪崩光电二极管具有低预击穿暗电流、72V稳定击穿（与器件直径无关），且具备覆盖2μm以上的清晰红外光响应。在78K温度下，器件外量子效率超过100%，在1.55μm处达163%，直接证实了雪崩倍增效应。这些结果表明，将窄带隙IV族吸收层与硅倍增区直接集成，是扩展硅雪崩光电探测光谱范围的可扩展策略，为传感、成像、通信、激光雷达及量子光子学领域的单片红外探测器开辟了路径。
英文摘要：
Silicon avalanche photodiodes provide a technologically mature platform for sensitive photodetection, but their spectral response is intrinsically limited by the silicon bandgap. Extending their operation into the infrared requires the integration of narrow-bandgap absorbers while preserving efficient avalanche multiplication and compatibility with silicon processing. Here, we propose and demonstrate a monolithic approach that combines direct, buffer-free growth of GeSn on silicon with a lateral thin-junction separate-absorption-multiplication architecture. The GeSn layer, with a Sn composition reaching 6 at.%, extends optical absorption to a wavelength of $2.6~μ$m, while avalanche multiplication is spatially confined to an ion-implanted silicon lateral junction. This separation enables independent control of infrared absorption and carrier multiplication without the thick Ge virtual substrates conventionally used for GeSn epitaxy. GeSn-on-Si avalanche photodiodes exhibit low pre-breakdown dark current, stable breakdown at 72 V independent of device diameter, and clear infrared photoresponse extending beyond $2~μ$m. At 78 K, the devices exhibit external quantum efficiency exceeding 100%, reaching 163% at $1.55~μ$m, providing direct evidence of avalanche multiplication. These results establish direct integration of narrow-bandgap group-IV absorbers with silicon multiplication regions as a scalable strategy for extending the spectral reach of silicon avalanche photodetection, opening a route toward monolithic infrared detectors for sensing, imaging, communications, LiDAR, and quantum photonics
