Abstract
Photodetectors are cornerstone components in integrated optical circuits and are essential for applications underlying modern science and engineering. Structures harnessing conventional crystalline materials are typically at the heart of such devices. In particular, group-IV semiconductors such as silicon and germanium open up more possibilities for high-performing on-chip photodetection thanks to their favorable electrical and optical properties at near-infrared wavelengths and processing compatibility with modern chip manufacturing. However, scaling the performance of silicon-germanium photodetectors to technologically relevant levels and benefiting from improved speed, reduced driving bias, enhanced sensitivity, and lowered power consumption arguably remains key for densely integrated photonic links in mainstream shortwave infrared optical communications. Here we report on a reliable 40 Gbps direct detection of chip-integrated silicon-germanium avalanche p-i-n photo receiver driven with low-bias supplies at 1.55 µm wavelength. The avalanche photodetection scheme calls upon fabrication steps commonly used in complementary metal-oxide-semiconductor foundries, alleviating the need for complex epitaxial wafer structures and/or multiple ion implantation schemes. The photo receiver exhibits an internal multiplication gain of 120, a high gain-bandwidth product up to 210 GHz, and a low effective ionization coefficient of ∼ 0.25 . Robust and stable photodetection at 40 Gbps of on–off keying modulation is achieved at low optical input powers, without any need for receiver electronic stages. Simultaneously, compact avalanche p-i-n photodetectors with submicrometric heterostructures promote error-free operation at transmission bit rates of 32 Gbps and 40 Gbps, with power sensitivities of − 12.8 d B m and − 11.2 d B m , respectively (for 10 − 9 error rate and without error correction coding during use). Such a performance in an on-chip avalanche photodetector is a significant step toward large-scale integrated optoelectronic systems. These achievements are promising for use in data center networks, optical interconnects, or quantum information technologies.
Highlights
Efficient and reliable photodetectors have been at the forefront of optoelectronics research and development since the rise of integrated optics
We demonstrate small-sized and high-performing Si–Ge–Si p-i-n photodetectors with double heterojunctions operated in the avalanche regime
The linear decrease of the breakdown bias with the shrinking of the intrinsic region width suggests that the same levels of the electric field are required to initiate an avalanche multiplication
Summary
Efficient and reliable photodetectors have been at the forefront of optoelectronics research and development since the rise of integrated optics. Photodetectors are enabling devices on the road toward applications in modern science and engineering. Photodetectors have primarily harnessed standard crystalline materials that, hinging upon their electronic bandgap, convert an optical signal into an electrical one [1,2,3]. Most optical receivers rely on photodiodes made of III-V and group-IV semiconductors, which are widely used in modern electronic and optoelectronic industries [4,5]. The optoelectronic characteristics of groupIV semiconductors, in particular, can be harnessed to fabricate advanced and scalable monolithic platforms [6,7,8,9,10].
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