CMOS-Compatible Micro Photovoltaic Generator with Post-Processing Enhanced Optical Absorption

Area of Science:

• Materials Science
• Electrical Engineering
• Semiconductor Physics

Background:

• Micro photovoltaic generators (MPGs) are crucial for harvesting optical energy.
• Standard CMOS technology offers a scalable platform for fabricating such devices.
• Optimizing junction design and optical coupling is key to improving MPG performance.

Purpose of the Study:

• To design and fabricate a silicon-based MPG using standard 0.18 μm CMOS technology.
• To enhance photocurrent generation through a grid-structured architecture.
• To improve optical coupling and reduce reflection losses via post-CMOS treatment.

Main Methods:

• Fabrication of a silicon MPG utilizing a 0.18 μm CMOS process.
• Implementation of a grid-structured architecture with patterned p-type regions in an n-well.
• Application of a post-CMOS wet etching process to remove silicon dioxide layers.

Main Results:

• The MPG features a grid-like p-n junction network, expanding junction area and enhancing carrier collection.
• Post-CMOS treatment effectively removed dielectric layers, enabling direct photon penetration and minimizing reflection.
• Under 1000 W/m² illumination, the device achieved an open-circuit voltage of 0.49 V, short-circuit current of 239 µA, and maximum power of 90 µW.
• An overall energy conversion efficiency of 12.9% was recorded.

Conclusions:

• The grid-structured junction design effectively boosts photocurrent generation.
• Post-processing removal of dielectric layers significantly enhances optical coupling and device performance.
• The fabricated silicon MPG demonstrates high efficiency, validating the integrated design and fabrication approach.