The research team of Cheng Buwen at the State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, has developed a silicon-based germanium-tin detector that works in the mid-infrared band. This is another important achievement of the team in germanium-tin optoelectronic devices after the progress in epitaxial growth of germanium-tin materials.

Mid-infrared photonics is promising for applications in biosensing, free-space communication and gas detection. As the mid-infrared application scenarios continue to expand, high integration, high reliability, low cost and small size are the trends in the development of mid-infrared photonics. Silicon-based mid-infrared optoelectronic integration technology utilizes advanced and mature CMOS processes to integrate microelectronics and optoelectronics on silicon chips, which can meet the needs of mid-infrared photonics development.

Germanium-tin, a group IV silicon-based semiconductor material, is an ideal material for the preparation of silicon-based mid-infrared optoelectronic devices as its optical band gap can be extended to mid-infrared by adjusting the group distribution ratio of the alloy. However, epitaxial germanium-tin films on silicon-based substrates suffer from lattice mismatch and tin susceptibility to partitioning, making the epitaxy of high-quality, high-tin-component germanium-tin difficult.

The team member, Associate Researcher Jun Zheng, focused on the research of germanium-tin optoelectronic materials and devices, investigated the growth mechanism and device physics of high tin-component germanium-tin materials, solved the strain chattering and tin partitioning problems of high tin-component germanium-tin, and prepared a high-speed silicon-based germanium-tin detector with a 3 dB bandwidth of 3 GHz and a detection cut-off wavelength of 3.3 μm.

The work on germanium-tin mid-infrared detectors marks an important advancement in molecular beam epitaxy of germanium-tin materials by scientists, which is of great scientific significance for the future realization of silicon-based infrared optoelectronic integrated chips.