Overcoming optical-electrical grid design trade-offs for cm2-sized high-power GaAs photonic power converters by plating technology

Abstract

The optimization of III-V-based photovoltaic cells involves addressing the trade-off between optical losses due to grid shading and electrical losses due to series resistance. In this work, we overcome the boundary conditions of this optimization problem by increasing the grid line height. Contrary to a few micrometer high evaporated metal grid lines, distributed circuit modeling of 1-cm² GaAs photonic power converters suggests that 15-μm high grid lines yield the best performances, especially for high-current operation in the 1 to 10 A cm⁻² range. We have successfully implemented a silver plating process into the fabrication scheme of these devices. Current–voltage measurements under intense illumination demonstrate fill factors above 80% at currents up to 35.8 A, highlighting the capability to extract such high currents without major series resistance losses. Under equivalent monochromatic input power of 62.6 W, this results in a maximum power output of 35.5 W from the 1-cm² single-junction photovoltaic cell. This development enables optical power links with largely increased power densities, reducing the material demand of precious semiconductors and associated costs.