Control of Crack Formation for the Fabrication of Crack-Free and Self-Isolated High-Efficiency Gallium Arsenide Photovoltaic Cells on Silicon Substrate

We proposed a new scheme, controlling the crack formation by notch patterns, to fabricate self-isolated high-efficiency gallium arsenide (GaAs)-based solar cells on a silicon (Si) substrate. The notch patterns introduced into the Si substrate were found to successfully generate the crack-free areas of 2 mm × 2 mm size separated by the cracks for the 5.8-μm-thick GaAs layers on it. The individual solar cells on the crack-free areas were confirmed to be electrically isolated from one another by the well-defined crack array. The open-circuit voltage and the efficiency of the crack-free cell were improved to 0.87 V and 18.0%, respectively, from 0.78 V and 14.7% for the cell with 33.2 cm
⁻¹
of linear crack density.