Development of GaAs//Si current-balanced dual junction solar cell integrated by surface-activated bonding

A thickness controlled dual junction GaAs//Si solar cell for current matching was fabricated and demonstrated. The optically thin GaAs top cell grown by metal-organic vapor phase epitaxy (MOVPE) was directly integrated on the Si bottom cell by surface-activated bonding (SAB) method. Owing to the optically thin (~300 nm) GaAs top sub-cell, the operation of current-matched dual junction cell was observed under the standard 1 SUN illumination.