P-type GIGS (CuIn1-xGaxSe2) thin films are electro-deposited on a p-type c-Si substrate with a galvanostatic mode to form CIGS(p)/c-Si(p) hetero-junction. The Ga content is varied up to x = 30%. The physical properties of formed GIGS films are characterized by XRD, SEM, EDS and UV-Visible spectroscopy. With x = 30%, we obtain a single chalcopyrite phase of GIGS with a tetragonal crystal structure, a high crystallinity, an orientation toward the (112) direction and a band gap energy of 1.40 eV. AM1.5 J-V performed on the CuI(0.7)G(0.3)Se(2)/c-Si hetero-junction reveals interesting photovoltaic parameters with an efficiency of 3.75%. In addition, using the energy diagram of the hetero-junction calculated with the Anderson model, we show that it could play a dual role when combined to a c-Si cell in a Ag-Al/c-Si(n(+))/c-Si(p)/CIGS(p)/Al new architecture. Therefore, in addition to its interesting photovoltaic parameters, this hetero-junction can substitute the BSF.