Fabrication and Characterization of Photovoltaic Microgenerators Using the Complementary Metal Oxide Semiconductor Process

Abstract

This study develops a photovoltaic microgenerator based on the complementary metal oxide semiconductor (CMOS) process. The photovoltaic microgenerator converts the absorbed light energy into electrical energy using the photovoltaic effect. The material for the photovoltaic microgenerator is silicon, and its structure consists of patterned p–n junctions. The design of the photovoltaic microgenerator utilizes a grid-like shape, forming a large-area p–n junction with a patterned p-doping and N-well structure to enhance the photocurrent and improve the device’s performance. The photovoltaic microgenerator is fabricated employing the CMOS process with post-processing step. Post-processing is applied to enhance the microgenerator’s light absorption and energy-conversion efficiency. This involves using wet etching with buffered-oxide etch (BOE) to remove the silicon dioxide layer above the p–n junctions, allowing direct illumination of the p–n junctions. The area of the photovoltaic microgenerator is 0.79 mm2. The experimental results show that under an illumination intensity of 1000 W/m2, the photovoltaic microgenerator exhibits an open-circuit voltage of 0.53 V, a short-circuit current of 233 µA, a maximum output power of 99 µW, a fill factor of 0.8, and an energy-conversion efficiency of 12.5%.