Liu Jingchuan, Li Zhenyu, Liu Xiaofei, Yan Wentao, Zhao Xingyan, Zheng Shaonan, Qiu Yang, Zhong Qize, Dong Yuan, Hu Ting
School of Microelectronics, Shanghai University, Shanghai 201800, China.
Shanghai Collaborative Innovation Center of Intelligent Sensing Chip Technology, Shanghai University, Shanghai 201800, China.
Micromachines (Basel). 2025 Apr 30;16(5):542. doi: 10.3390/mi16050542.
Benefiting from the progress of the germanium (Ge) epitaxy process on silicon (Si) substrates, waveguide-integrated Ge-on-Si photodetectors (PDs) have demonstrated decent performances in short-wave infrared (SWIR) detection. By lowering the operating temperature, theses PDs can meet the stringent signal-to-noise requirements for high-sensitivity detection. We systematically investigated the dark current characteristics and optical response in the 1500-1600 nm wavelength range of the waveguide-integrated Ge-on-Si PDs operated at low temperatures (200 K to 300 K). Under a -3 V bias, the PD exhibits a room-temperature dark current of 4.62 nA and a responsivity of 0.87 A/W at 1550 nm. When the temperature was reduced to 200 K, the dark current decreased to 93.69 pA, and the responsivity dropped to 0.34 A/W. Using finite-difference time-domain (FDTD) and technology computer-aided design (TCAD) simulations, we extracted the absorption coefficients of epitaxial Ge on Si at low temperatures. At room temperature, the absorption coefficient at the wavelength of 1550 nm was approximately 1100 cm, while at 200 K, the absorption coefficient decreased to 248 cm. The outcomes of this work pave the way for the high-performance low-temperature Si photonic systems in the future.
受益于硅（Si）衬底上锗（Ge）外延工艺的进展，波导集成的硅基锗光电探测器（PD）在短波红外（SWIR）探测中展现出了良好的性能。通过降低工作温度，这些光电探测器能够满足高灵敏度探测对严格信噪比的要求。我们系统地研究了在低温（200 K至300 K）下工作的波导集成硅基锗光电探测器在1500 - 1600 nm波长范围内的暗电流特性和光响应。在-3 V偏压下，该光电探测器在室温下的暗电流为4.62 nA，在1550 nm处的响应度为0.87 A/W。当温度降至200 K时，暗电流降至93.69 pA，响应度降至0.34 A/W。我们利用时域有限差分（FDTD）和技术计算机辅助设计（TCAD）模拟，提取了低温下硅上外延锗的吸收系数。在室温下，1550 nm波长处的吸收系数约为1100 cm，而在200 K时，吸收系数降至248 cm。这项工作的成果为未来高性能低温硅光子系统铺平了道路。
