GaAs solar cell on Si substrate with good ohmic GaAs/Si interface by direct wafer bonding

•We report wafer bonding (WB) techniques giving good ohmic interfaces of GaAs/Si.•WB with a low bonding temperature and short processing time was performed.•We demonstrated the GaAs solar cell on Si substrate by WB techniques.•Fabricated GaAs solar cell on Si exhibited a comparable performance with that on GaAs.•We proved the feasibility of stable WB technologies of GaAs/Si substrates.

In this work, we developed wafer bonding techniques to bond GaAs and Si wafers. Wafer bonding was carried out at room temperature without high temperature annealing processes. The bonded interface showed a low interface resistance of 8.8×10−3 Ω cm2. We also exploited the new bonding techniques to fabricate a GaAs solar cell on a Si substrate. The solar cell showed a high energy conversion efficiency (13.25%) even without an anti reflection coating. The performance of the fabricated GaAs/Si solar cell was comparable to that of a homogeneous GaAs solar cell grown on a GaAs substrate. *Corresponding author.