Impacts of Dislocations and Residual Thermal Tension on Monolithically Integrated InGaP/GaAs/Si Triple‐Junction Solar Cells

Direct epitaxy of III−V materials on Si is a promising approach for highly stable, scalable, and efficient Si‐based multijunction solar cells. However, challenges lie in overcoming epitaxial dislocations and residual thermal strain generated by lattice constant and thermal‐expansion‐coefficient mismatches, respectively. Herein, a 15.2% efficient InGaP/GaAs/Si triple‐junction solar cell with an open‐circuit voltage of 2.36 V by using In 0.10 Al 0.16 Ga 0.74 As digital‐alloy dislocation filter layers is first demonstrated. The filter layers are utilized in the n‐GaAs buffer on Si to reduce threading dislocation density to 4 × 10 7 cm −2 while maintaining optical transparency to Si bottom cell. Then, the impacts of threading dislocations and residual tension on InGaP/GaAs/Si cells are systematically investigated by comparing them to the co‐grown InGaP/GaAs tandem cells on a native GaAs substrate. Based on the comparative analysis, a strategy to suppress material deformation and defect formation toward 30% efficient InGaP/GaAs/Si triple‐junction solar cells is proposed.