Dr. Mukul Kumar is a Postdoctoral Researcher at the Graduate Institute of Photonics and Optoelectronics, National Taiwan University (NTU), Taipei, Taiwan. He received his Ph.D. in Photonics and Optoelectronics from NTU in January 2025 and holds an M.Tech. in Electronics and Communication Engineering from the Indian Institute of Technology (IIT) Dhanbad, India.

His research expertise includes semiconductor device physics, device modeling and simulation, compound and wide-bandgap semiconductors, optoelectronic devices, and device fabrication and characterization. His current research focuses on oxide semiconductor thin-film transistors, light-emitting transistors, heterojunction phototransistors, GaN high-electron-mobility transistors, silicon photonics, and advanced semiconductor integration technologies.

Dr. Kumar has authored and co-authored research publications in leading journals, including IEEE Transactions on Electron Devices and IEEE Electron Device Letters. His research contributions include the design and development of light-emitting transistor-based thermal sensors, optoelectronic encoders, and advanced semiconductor devices. He has presented his work at several international conferences and received research scholarships, travel grants, and recognition for his academic and research achievements.

In addition to his research activities, Dr. Kumar serves as a Chapter Secretary Officer of the IEEE Photonics Society Taipei Section Chapter and as a Counselor for the IEEE National Taiwan University Student Branch. He is actively involved in academic event organization, peer review, and mentoring students and early-career researchers.

Through his work in semiconductor devices, photonics, and emerging electronic technologies, Dr. Kumar contributes to advancing semiconductor research and next-generation optoelectronic applications.

Light-Emitting Transistors for Smart Thermal Sensing: From Device Physics to Integrated Optoelectronic Technologies

Light-emitting transistors (LETs) are multifunctional semiconductor devices that integrate transistor operation with light emission, providing unique opportunities for optoelectronic and sensing applications. In addition to their conventional electrical and optical functionalities, LETs exhibit strong temperature-dependent electrical characteristics, making them promising candidates for highly sensitive thermal sensing.

In this talk, I will present the device physics, design, and thermal-sensing characteristics of light-emitting transistors based on III–V compound semiconductor heterostructures. The temperature-dependent carrier transport and recombination mechanisms responsible for the enhanced thermal response will be discussed. Experimental results demonstrating significant temperature-dependent collector current and voltage responses will be presented, together with the design strategies used to improve thermal sensitivity and device performance. The development of quantum-well and multi-quantum-well heterostructure devices will also be discussed to illustrate how device engineering can enhance temperature sensitivity.

Beyond individual devices, I will introduce LET-based functional circuits and optoelectronic sensing concepts, including transistor-based thermal sensing and light-emission-enabled signal generation. These results demonstrate the potential of LETs as a platform for compact, multifunctional, and highly sensitive thermal sensing technologies.

Finally, future research directions toward integrated thermal sensing, smart optoelectronic systems, and multifunctional semiconductor devices will be discussed. The talk will highlight how the integration of electrical, optical, and thermal functionalities within a single transistor can open new opportunities for next-generation sensing and intelligent electronic systems.

Dr. Mukul Kumar is a Postdoctoral Researcher at the Graduate Institute of Photonics and Optoelectronics (GIPO), National Taiwan University (NTU), Taiwan. He received his Ph.D. in GIPO from NTU in 2025, and his M.Tech. and B.Tech. degrees in Electronics and Communication Engineering from the Indian Institute of Technology (IIT) Dhanbad and Jaypee University of Engineering and Technology (JUET), India, respectively.

His research interests include semiconductor device physics, III–V compound semiconductor optoelectronic devices, light-emitting transistors (LETs), heterojunction bipolar transistors, transistor lasers, emerging oxide semiconductor thin-film transistors, wide-bandgap semiconductor devices, CPO, TSV and TCAD-based device modeling and simulation. His doctoral research focused on the design, fabrication, and optimization of LET-based thermal sensors for smart sensing technologies. His work has demonstrated ultra-high thermal current sensitivity of up to 26.2 μA/°C and voltage sensitivity of 9.12 mV/°C, advancing the potential of LETs for highly sensitive thermal sensing and integrated optoelectronic applications. He has published research in leading journals, including IEEE Transactions on Electron Devices and IEEE Electron Device Letters. Dr. Kumar currently serves as Secretary of the IEEE Photonics Society Taipei Section Chapter and Counselor of the IEEE NTU Student Branch. He is also an active international mentor and actively contributes to international research collaboration, student mentoring, and professional activities in photonics and semiconductor technologies.