Cariou, RomainRomainCariouBenick, JanJanBenickBeutel, PaulPaulBeutelRazek, N.N.RazekFlötgen, C.C.FlötgenHermle, MartinMartinHermleLackner, DavidDavidLacknerGlunz, Stefan W.Stefan W.GlunzBett, Andreas W.Andreas W.BettWimplinger, M.M.WimplingerDimroth, FrankFrankDimroth2022-03-052022-03-052017https://publica.fraunhofer.de/handle/publica/24765410.1109/jphotov.2016.2629840Stacking III-V p-n junctions on top of wafer-based silicon solar cells is a promising way to go beyond the silicon single-junction efficiency limit. In this study, triple-junction GaInP/AlxGa1-xAs//Si solar cells were fabricated using surface-activated direct wafer bonding. Metal-organic-vapor-phase-epitaxy-grown GaInP/AlxGa1-xAs top cells are bonded at low temperature to independently prepared wafer-based silicon cells. n-Si//n-GaAs interfaces were investigated and achieved bulk-like bond strength, high transparency, and conductivity homogeneously over 4-inch wafer area. We used transfer-matrix optical modeling to identify the best design options to reach current-matched two-terminal devices with different mid-cell bandgaps (1.42, 1.47, and 1.52 eV). Solar cells were fabricated accordingly and calibrated under AM1.5g 1-sun conditions. An improved Si back-side passivation process is presented, leading to a current density of 12.4 mA/cm2 (AM1.5g), measured for a flat Si cell below GaAs. The best 4 cm2 GaInP/GaAs//Si triple-junction cell reaches 30.2% 1-sun efficiency.enMaterialien - Solarzellen und TechnologiePhotovoltaikSilicium-PhotovoltaikIII-V und Konzentrator-PhotovoltaikEpitaxieSi-Folien und SiC-Abscheidungensiliconwafer bondingtriple junction solar cellsjournal article