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A research article by the CCU Mechanical Engineering team is published in Advanced Photonics Research with its newly developed GeSn Waveguide Photodetectors for optical communication

 

As the Internet rapidly becomes widespread around the globe, the amount of data transmission is growing exponentially, and humans can barely live without the Internet. Thus, the importance of implementing fiber-optic communication systems has been much emphasized these days. To overcome the problems associated with the gradually saturated transmission capacity of optical communication devices, Dr. Guo-En Chang, a professor at the Department of Mechanical Engineering of National Chung Cheng University (CCU), developed a semiconductor photodetector device by using GeSn as the core material to tackle the task. The superior technology enables the mass production of low-cost optoelectronic devices and helps the team reach its global pioneer status in power conversion efficiency and photodetection range. Recently, Dr. Chang’s research on the GeSn Waveguide Photodetectors has also been selected as the cover picture of the world-renowned journal Advanced Photonics Research.

 

“Since everyone uses a lot of social media, such as YouTube, Google, and Facebook, to receive massive audiovisual content every day, the demand for faster internet transmission speed is increasing.” Dr. Chang said that the global network has entered a new era of fiber-optic communication, but the current near-infrared communication structure is becoming more and more limited in its transmission capacity and cannot meet the needs generated in the new era. Therefore, Dr. Chang led a team of graduate students to blaze a trail to improve the internet transmission speed by applying mid-infrared light and developing a GeSn waveguide photodetector (WGPD) for the photonic integrated circuit in the 2μm wavelength band.

 

“In general, if we use light to transmit signals, we need a device to convert them into electrical signals so that our cellphones and computers can read them. And the photodetector is the exact device for the conversion.” Dr. Chang said that the optoelectronic devices used in optical communication are mostly III-V semiconductors, which are more expensive and complicated to produce and can only be made in specific wafer fabrication plants. However, the optoelectronic device newly developed by the CCU Mechanical Engineering team is compatible with the production line and manufacturing process of Taiwan’s advanced semiconductor companies like Taiwan Semiconductor Manufacturing Co., Ltd. (TSMC) and can be quickly produced in large quantities and at low cost. In addition, unlike general semiconductor technologies that can only be applied in the near-infrared band, the GeSn WGPD made by the CCU team can be applied even in the mid-infrared range.

 

Starting when Dr. Chang began to teach at CCU ten years ago, he and the CCU team have placed a great emphasis on the synthesis, design, manufacture, and characterization of innovative optoelectronic devices. In 2014, they even took the lead in developing the world’s first GeSn WGPD device. “Germanium (Ge) and tin (Sn) are not exactly compatible. The physical limit of the fusion of Sn into Ge is only 1% in current technologies, but our technology can break the limit and raise the Sn content to at least 10%.” Dr. Chang stated that only 10 teams in the world can successfully combine the Ge and Sn materials now, and the CCU team is one of the ten and the first team to possess GeSn semiconductor material technology in Taiwan. He further mentioned that apart from optical communication, mid-infrared light can also be applied to diverse aspects, such as optical radar, biomedicine, and gas sensing.

 

Even though there are a lot of unknowns in this new type of material for photodetector devices, including different manufacturing processes and parameters from the original ones and the need to modify the measurement system, the CCU team has still been striving to improve its technology in the manufacturing of GeSn WGPDs. This year, the CCU team successfully developed the fourth generation of the GeSn optoelectronic device and published its breakthroughs and observations in a research article in the international journal Advanced Photonics Research. Since the optical-electrical conversion performance and the detection range of the GeSn WGPD developed by CCU have been the edge all over the world, the fruit of the research has received much attention and was selected as the cover picture of the July issue of the journal. Dr. Guo-En Chang indicated that it was an honor for their research to be approved by Advanced Photonics Research, a journal that focuses on the relevant fields of advanced materials and photonics and is published by the world-renowned publishing company Wiley. For being able to keep up with the top teams abroad with their research, the students and the CCU team deserve all the credit for their effort and devotion.

Link to the research article: https://doi.org/10.1002/adpr.202100330
 

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