Epitaxial growth and characterization of III-V group solar cell structures

In this study, the epitaxial structure of III-V compound double junction GaxIn1-xP/GaAs and triple junction GaxIn1-xP/GaAs/Ge solar cells was designed and the suitable structures for device application were grown using MBE technique. Firstly, the first junction of the triple junction cell, p-n junction Ge cell, was calibrated and grown. The deposition of As layers on five pieces of Ge substrate was carried out at different substrate and annealing temperatures by migration enhanced epitaxy (MEE) and the p-n junction was formed. After the completion of Ge cell calibration, the second cell, p-n junction GaAs cell, was grown on Ge cell and the characterization of GaAs/Ge double junction solar cell was done. Then, three GaxIn1-xP ternary alloys with different composition were separately grown on GaAs substrates and characterized for the calibration of alloy ratio. After the calibration of GaxIn1-xP structure, double junction GaxIn1-xP/GaAs cell was grown and characterized. Finally, this study is completed by growing and characterizing triple junction GaxIn1-xP/GaAs/Ge cell. For the structural, electrical and optical characterization of the structures, HR-XRD, SIMS, PL, AFM, SE and HMS systems were used.