In this interview, Mr. Moussa Cissé, a PhD researcher at IMS – Laboratory for the Integration from Material to Systems (University of Bordeaux, France), shares insights into his doctoral research and its connection to the Move2THz project. His work focuses on advancing Indium-Phosphide (InP) double heterojunction bipolar transistors (DHBTs), a crucial technology for enabling next-generation mobile communications, including 6G. We also discuss the technical challenges he faces working on the project, his professional growth, and the broader opportunities in the semiconductor industry, particularly in the field of sub-THz communications.

Q: 𝑪𝒂𝒏 𝒚𝒐𝒖 𝒅𝒆𝒔𝒄𝒓𝒊𝒃𝒆 𝒚𝒐𝒖𝒓 𝒅𝒐𝒄𝒕𝒐𝒓𝒂𝒍 𝒓𝒆𝒔𝒆𝒂𝒓𝒄𝒉 𝒕𝒐𝒑𝒊𝒄/𝒂𝒓𝒆𝒂 𝒂𝒏𝒅 𝒉𝒐𝒘 𝒊𝒕 𝒓𝒆𝒍𝒂𝒕𝒆𝒔 𝒕𝒐 𝒕𝒉𝒆 𝑴𝒐𝒗𝒆2𝑻𝑯𝒛 𝒑𝒓𝒐𝒋𝒆𝒄𝒕?
A: My doctoral research focuses on “On-wafer RF characterization of Indium-Phosphide (InP) double heterojunction bipolar transistors (DHBTs)” through a collaboration with both III-V Lab and ETH-Zurich. This work aligns closely with the objectives of the Move2THz project, which seeks to leverage the high-frequency capabilities of InP technology and combine it with the large-scale integration potential of silicon platforms to enable the next generation of mobile communications (6G). Then, the InP device characterization represents an indispensable step, which intends to extract key parameters such as fT (transition frequency) and fmax (maximum oscillation frequency), essential metrics for building compact models that facilitate the design of high-performance RF circuits.

Q: 𝑾𝒉𝒂𝒕 𝒑𝒆𝒓𝒔𝒐𝒏𝒂𝒍𝒍𝒚 𝒊𝒏𝒔𝒑𝒊𝒓𝒆𝒅 𝒚𝒐𝒖 𝒕𝒐 𝒕𝒂𝒌𝒆 𝒕𝒉𝒆 𝒄𝒉𝒂𝒏𝒄𝒆 𝒕𝒐 𝒘𝒐𝒓𝒌 𝒐𝒏 𝒕𝒉𝒆𝒔𝒆 𝒕𝒆𝒄𝒉𝒏𝒐𝒍𝒐𝒈𝒊𝒆𝒔 𝒂𝒏𝒅 𝒐𝒏 𝒕𝒉𝒊𝒔 𝒑𝒓𝒐𝒋𝒆𝒄𝒕?
A: I have always been fascinated by the potential of high-frequency semiconductor technologies. InP, in particular, due to its exceptional electron mobility and high breakdown voltage, making it ideal for high-speed and high-power applications (RF & mmW). I am excited to work on this project for its ambition to contribute to the European leadership in 6G technologies by addressing the challenges of sub-THz communication.

Q: 𝑾𝒉𝒊𝒄𝒉 𝒐𝒓𝒈𝒂𝒏𝒊𝒔𝒂𝒕𝒊𝒐𝒏 𝒂𝒓𝒆 𝒚𝒐𝒖 𝒘𝒐𝒓𝒌𝒊𝒏𝒈 𝒘𝒊𝒕𝒉 𝒐𝒏 𝒕𝒉𝒆 𝑴𝒐𝒗𝒆2𝑻𝑯𝒛 𝒑𝒓𝒐𝒋𝒆𝒄𝒕? 𝑪𝒂𝒏 𝒚𝒐𝒖 𝒅𝒆𝒔𝒄𝒓𝒊𝒃𝒆 𝒚𝒐𝒖𝒓 𝒓𝒐𝒍𝒆 𝒘𝒊𝒕𝒉𝒊𝒏 𝒕𝒉𝒆 𝒕𝒆𝒂𝒎 𝒂𝒏𝒅 𝒚𝒐𝒖𝒓 𝒑𝒓𝒊𝒎𝒂𝒓𝒚 𝒓𝒆𝒔𝒑𝒐𝒏𝒔𝒊𝒃𝒊𝒍𝒊𝒕𝒊𝒆𝒔?
A: I am working in the “Model for Circuit” team, which is included in the “Circuit Design” research group in the IMS Laboratory (Integration from Material to System). My role in the team mainly concerns the RF characterization of InP devices, focusing on the extraction of their high-frequency performance metrics (fT, fmax) and high-frequency noise parameters. I am also responsible for the design of RF test structures by using EM simulation predictive capabilities and low-noise amplifier (LNA) circuit block design as demonstrators for sub-THz applications.

Q: 𝑾𝒉𝒐 𝒅𝒐 𝒚𝒐𝒖 𝒄𝒐𝒍𝒍𝒂𝒃𝒐𝒓𝒂𝒕𝒆 𝒘𝒊𝒕𝒉 𝒎𝒐𝒔𝒕 𝒐𝒇𝒕𝒆𝒏, 𝒂𝒏𝒅 𝒘𝒉𝒂𝒕 𝒅𝒐𝒆𝒔 𝒕𝒉𝒂𝒕 𝒄𝒐𝒍𝒍𝒂𝒃𝒐𝒓𝒂𝒕𝒊𝒐𝒏 𝒍𝒐𝒐𝒌 𝒍𝒊𝒌𝒆?
A: I collaborate frequently with researchers and professors who are experts in RF characterization. While I perform a significant portion of my work independently, particularly the experimental and simulation aspects, this independence is complemented by regular discussions and feedback sessions with team members to ensure alignment with the broader objectives of the Move2THz project.

Q: 𝑾𝒉𝒂𝒕 𝒔𝒑𝒆𝒄𝒊𝒇𝒊𝒄 𝒕𝒆𝒄𝒉𝒏𝒊𝒄𝒂𝒍 𝒐𝒓 𝒑𝒓𝒐𝒇𝒆𝒔𝒔𝒊𝒐𝒏𝒂𝒍 𝒔𝒌𝒊𝒍𝒍𝒔 𝒉𝒂𝒗𝒆 𝒚𝒐𝒖 𝒅𝒆𝒗𝒆𝒍𝒐𝒑𝒆𝒅 𝒕𝒉𝒓𝒐𝒖𝒈𝒉 𝒕𝒉𝒊𝒔 𝒋𝒐𝒃?
A: On-wafer RF characterization of active and passive devices, S-parameter measurement, high frequency noise measurement, Passive test structures design and modelling, EM simulation and RF/mmW circuits design.

Q: 𝑾𝒉𝒂𝒕 𝒉𝒂𝒔 𝒃𝒆𝒆𝒏 𝒕𝒉𝒆 𝒃𝒊𝒈𝒈𝒆𝒔𝒕 𝒄𝒉𝒂𝒍𝒍𝒆𝒏𝒈𝒆 𝒊𝒏 𝒚𝒐𝒖𝒓 𝒓𝒐𝒍𝒆 𝒔𝒐 𝒇𝒂𝒓, 𝒂𝒏𝒅 𝒉𝒐𝒘 𝒅𝒊𝒅 𝒚𝒐𝒖 𝒂𝒅𝒅𝒓𝒆𝒔𝒔 𝒊𝒕?
A: One of the challenges I have encountered is the accurate extraction of RF performance parameters (such as fT and fmax) from the measurement datas, particularly at high frequencies. To address this, I optimized the de-embedding techniques used during on-wafer measurements, and refined the design of test structures to minimize parasitic effects (inductances and capacitances). This iterative process ensures more reliable data and models for circuit design.

Q: 𝑺𝒆𝒎𝒊𝒄𝒐𝒏𝒅𝒖𝒄𝒕𝒐𝒓 𝒕𝒆𝒄𝒉𝒏𝒐𝒍𝒐𝒈𝒊𝒆𝒔 𝒆𝒗𝒐𝒍𝒗𝒆 𝒓𝒂𝒑𝒊𝒅𝒍𝒚. 𝑯𝒐𝒘 𝒅𝒐 𝒚𝒐𝒖 𝒔𝒕𝒂𝒚 𝒖𝒑𝒅𝒂𝒕𝒆𝒅 𝒘𝒊𝒕𝒉 𝒏𝒆𝒘 𝒂𝒅𝒗𝒂𝒏𝒄𝒆𝒎𝒆𝒏𝒕𝒔?
A: To stay informed about advancements in semiconductor technologies, I regularly read articles from journals like IEEE, participate in seminars and workshops organized by IMS Laboratory, work on open source projects related to semiconductors technologies, and follows industry leaders’ social medias.

Thank you for your thoughtful responses, Mr. Moussa Cissé. We wish you continued success with your research!