A method of manufacturing a solar cell by providing a first semiconductor substrate and depositing a first sequence of layers of semiconductor material to form a first solar subcell, including a first bond layer disposed on the top of the first sequence of layers. A second semiconductor substrate is provided, and on the top surface of the second substrate a second sequence of layers of semiconductor material is deposited forming at least a second solar subcell. A second bond layer is disposed on the top of said second sequence of layers. The first solar subcell is mounted on top of the second solar subcell by joining the first bond layer to the second bond layer in an ultra high vacuum chamber, and the first semiconductor substrate is removed.