We report on the fabrication of III-V compound semiconductor multi-junction solar cells using the room-temperature wafer bonding technique. GaInP/GaAs dual-junction solar cells on GaAs substrate and InGaAsP single junction solar cell on InP substrate were separately grown by all-solid state molecular beam epitaxy (MBE). The two cells were then bonded to a triple-junction solar cell at room-temperature. A conversion efficiency of 30.3% of GaInP/GaAs/InGaAsP wafer-bonded solar cell was obtained at 1-sun condition under the AM1.5G solar simulator. The result suggests that the room-temperature wafer bonding technique and MBE technique have a great potential to improve the performance of multi-junction solar cell. (C) 2016 Elsevier B.V. All rights reserved.