(Japanese version：https://blog.fltech.dev/entry/2024/10/15/sakutai74-ja)
Hello. I'm Hiroyoshi Ohtsu from Devices & Materials Research Center. I have attended and presented at the 74th Conference of Japan Society of Coordination Chemistry held at Gifu University and Nagaragawa International Conference Center from September 18 to 20, 2024. At the conference, I presented my research results on the chemistry of compound semiconductor processes. Here, I introduce the contents of the conference and my presentation.
Japan Society of Coordination Chemistry ~What is Coordination Chemistry? ~
The Japan Society of Coordination Chemistry (JSCC) is an academic society specializing in a field of chemistry called Coordination Chemistry focusing on Complexes or Coordination Compounds.
Do you know what Complexes are? Actually, they are very familiar to us. For example, the red color of the blood flowing our bodies comes from iron "complexes ” in hemoglobin. Complexes also exist in many other places, such as in the leaves of plants. A complex is a general term for a molecule that is formed by attaching an organic molecule (called a ligand) to a metal ion using a coordination bond. The image of a complex is shown in the figure with the iron complex of hemoglobin.
The functions of such “complexes” have long been studied, focusing on the functionality obtained through the interaction between the metal ion and the organic ligands. For example, cisplatin, an anticancer drug, is a complex of platinum (Pt) that shows anticancer effects when platinum coordinates with cancer cells. Various complexes/coordination compounds are being investigated to exploit their unique functionalities (coordination chemistry). The Japan Society of Coordination Chemistry (JSCC) is the organization that studies complexes, with nearly 1,000 members, including regular and student members, though most are from academia.
At the Japan Society of Coordination Chemistry conference, research on complexes was presented from various chemical perspectives. As is typical in the field of chemistry, a wide range of sessions were held simultaneously, covering topics from the synthesis of new complexes to the functions and applications of complexes. Many of the presentations were based on fundamental science, such as the relationship between the molecular structure and physical properties of complexes. However, there is a growing focus on green materials for a sustainable society, such as catalysts for carbon dioxide reduction and adsorbent materials for carbon dioxide using porous materials called Metal-Organic Frameworks (MOFs). Research on green-oriented materials is also increasing.
At this conference, I presented my results on Chemistry of Compound Semiconductor Processes . This is the result of my research on the chemistry of the wet etching process of GaSb substrates and the “complexes” involved in the process.
Chemistry of Semiconductor Processes! ～The existence of complexes in semiconductor processes~
Compound semiconductors are used for high electron mobility transistor (HEMT) and infrared absorption devices because they offer performance that cannot be achieved by Si semiconductors. Their device properties are influenced not only by the device structure but also by the semiconductor processes. In particular, wet etching significantly impacts performance, making it important to chemically analyze what occurs during wet etching to establish guidelines for future performance control. In this study, GaSb (gallium antimonide) was selected as the compound semiconductor, and its behavior in the etching solution was experimentally clarified.
The method is relatively simple: GaSb substrates are immersed in etchant, and the solution is observed using various chemical analyses. Using absorption spectroscopy, mass spectrometry, and electrochemical measurements on a solution after etching of GaSb, it was found that an antimony (Sb) complex is formed. In the etchant, citric acid plays a key role in complex formation as a chelating agent. Citric acid, a compound commonly found in lemons, is the source of this complex formation. You may have used it as a cleaning agent in your kitchen or bath—this, too, is a function of complex formation.
This presentation was given as a poster, and I had meaningful and stimulating discussions with participants involved in complex chemistry. In the future, we aim to elucidate the relationship between device performance and complex formation.
- Presentation title: Behavior of GaSb substrates in etching solution, The 74th Conference of Japan Society of Coordination Chemistry, 3PF-22
Current Trends in Coordination Chemistry: Toward Green Materials
Coordination chemistry is a fundamental science that is sowing the seeds of technologies for the future. A major current trend is the development of green materials that contribute to a sustainable society. For example, various materials—such as catalysts for converting atmospheric carbon dioxide, a greenhouse gas, into petroleum fuel, and thermochemical battery materials that convert heat into electricity—are being developed for future applications. The unique concerted function of metal ions and organic ligands in complexes is expected to play a key role in these applications.
Last but not least: a visit to Gifu
I visited Gifu University and the Nagaragawa International Conference Center to participate in the conference. Gifu is easily accessible, only 20 minutes from Nagoya by train. Gifu is often associated with Nobunaga Oda, and Gifu Castle is indeed a great spot from which to view the surroundings. While looking at Gifu Castle, I realized that research is similar—a broad view is important. The photo shows Gifu Castle and the Nagara River, as seen from the Nagaragawa International Conference Center.
.
