Optimization of Bonded III-V on Si Multi-Junction Solar Cells

In this work, a high efficiency III-V on Si 3-junction solar cell achieved through intermediate metal connection and areal current matching is presented. The cell has an efficiency of 25.8% under 1 sun AM 1.5G. Factors that are important to the further improvement of the cell performance are discussed. By advanced optical coupling methods, the reflection loss at the bonding interface can be reduced to less than 5%. Shadowing loss can be reduced to less than 10% by using aligned intermediate metal contact schemes. The bonding resistance is measured to be around 0.012 Ohm-cm2, enabling operation of the cell up to illumination of 50 suns. This work also discusses the enhanced resistance to spectral variations for multi-junction cells operating under varying environmental conditions using the areal current matching technique.