【电气论坛】Maximizing the efficiency of CMOS front-illuminated photovoltaic for self-powered sensor applications(IGBSG 2019) 国际会议专题报告（4）
Maximizing the efficiency of CMOS front-illuminated photovoltaic for self-powered sensor applications
主 讲 人
Prof. Poki Chen
Poki Chen was born in Chia-Yi, Taiwan, R.O.C., in 1963. He received the B.S., M.S. and Ph.D. degrees in Electrical Engineering Department from National Taiwan University (NTU), Taipei, Taiwan, in 1985, 1987 and 2001, respectively. During 1998-2001, 2001-2006 and 2006-2011 he was a Lecturer, an Assistant Professor, and an Associate Professor correspondingly in Electronic Engineering Department of National Taiwan University of Science and Technology (NTUST). He is a Professor in Electronic and Computer Engineering Department of NTUST. Currently, he serves as the Associate Editors for IEEE Transactions on Very Large Scale Integration Systems (TVLSI) and IEEE Access since 2011 and 2013. He is the organizer of IEEE International Conference on Intelligent Green Building and Smart Grid (IGBSG) since 2014 and serves as keynote/invited speakers, TPC members, session chairs for various IEEE conferences, such as SOCC, VLSI-DAT, IFEEC, ISESD, NoMe TDC, ISNE, ASID … and so forth. His research interests include analog / mixed-signal IC design and layout with special interest in time-domain signal processing circuits, such as time-domain smart temperature sensor, time-to-digital converter (TDC), digital pulse converter (DTC), time-domain ADC and high accuracy DAC. He is also interested in creating innovative analog applications for FPGA platforms, such as FPGA smart temperature sensor, FPGA digital-to-time and time-to-digital converters.
There is a tremendous need for sensors to accommodate the booming markets for IoT, Industry 4.0, intelligent building, environmental monitoring, home security and care, health care system and even implanted electronic medicine. One of the major challenges is to power such enormous sensors in an efficient and inexpensive way. Either wired or wireless power supply is not only money- but also time-wasting for outdoor applications. Energy harvestings become popular and viable solutions to compose the so-called self-power sensors. Among them, on-chip solar cell gets much more attention than the others due to its readiness and easiness to access.
To get high conversion efficiency, back-illuminated solar cell can be adopted. However, it requires expensive non-standard processing such as substrate thinning, substrate removal, surface texturing and Integrated Passive Devices (IPD) flip-chip packaging. To be fully integrated with the standard CMOS circuits, front-illuminated solar cell is a much better alternative at the expense of lower efficiency due to the shielding effect of metal lines for photocurrent conduction. Different CMOS layers and layout topologies are explored to increase the PN junction depletion region density per area and the corresponding aperture ratio to enhance the conversion efficiency. The photovoltaic chips from a few batches and processes are measured and compared. Some easy-to-understand rules are summarized to maximize the output power of front-illuminated CMOS solar cell. With the standard TSMC 0.18mm CMOS process, a record-breaking 31.5% conversion efficiency is finally achieved.