On-chip solar power source for self-powered smart microsensors in bulk CMOS process

Area of Science:

• Materials Science
• Electrical Engineering
• Renewable Energy

Background:

• On-chip solar cells are vital for self-powered microsensors in the Internet of Things (IoT).
• Improving photoelectric conversion efficiency (PCE) is key to advancing solar energy harvesting.
• Surface electrode shadowing limits the efficiency of conventional on-chip solar cell designs.

Purpose of the Study:

• To enhance the photoelectric conversion efficiency of on-chip solar cells.
• To reduce the shadowing effect caused by surface electrodes.
• To improve solar energy harvesting for self-powered IoT applications.

Main Methods:

• Fabrication of a segmented triple-well on-chip solar cell using a standard 0.18 μm CMOS process.
• Implementation of a center electrode (CE) layout to minimize shadowing.
• Integration of highly doped interconnections for improved performance.
• Testing under solar simulator illumination and evaluation of end-to-end conversion efficiency.

Main Results:

• Achieved a photoelectric conversion efficiency of 25.79% under illumination.
• Demonstrated a 17.49% improvement compared to conventional ring electrode (RE) designs.
• Obtained a maximum end-to-end energy harvesting conversion efficiency of 10.20%.
• Ensured a stable 1V output under varying illumination and load conditions.

Conclusions:

• The center electrode (CE) layout effectively reduces shadowing, enhancing on-chip solar cell efficiency.
• The developed on-chip solar cell offers a significant improvement for solar energy harvesting in IoT devices.
• The system provides reliable power output, suitable for self-powered smart microsensors.