III–V-N compounds for multi-junction solar cells on Si

We proposed a GaPN/GaAsPN/Si multi-junction solar cell in which lattice constants for all layers matched to Si bottom cell. Initial growth of GaP layer on Si is an important role to suppress the anti-phase domain, stacking faults, threading dislocations and melt-back etching. According to theoretical estimation considering the strain effect, band-gap energy about 1.65 eV can be obtained by GaAs_0.2P_0.74N_0.06 which satisfies the lattice-matching condition to Si. In order to clarify the possibility of this material system, we grew GaPN and GaAsPN on the structural defect-free GaP/Si template by using rf-MBE. We also investigated the pinning state at the GaP(N)/Si heterointerface to design a low-loss tunneling junction.