A study on Cu metallization for crystalline Si solar cells

Cu metallization for crystalline Si solar cells was investigated with the diffusion barrier of either Ti or Ti/TiN. The resistivity and specific contact resistance change of both Ti(30 nm)/Cu(100 nm) and Ti(30 nm)/TiN(30 nm)/Cu (100 nm) layers for various annealing temperatures were investigated. As the annealing temperature increased, the efficiency of cells increased mainly due to the increase in FF and I_SC, which correlates with R_S of the metal layer. The fabricated solar cells with Ti/TiN/Cu layer generally showed higher efficiencies than those with Ti/Cu, because in Ti/Cu layer Cu diffused through Ti and acted as the deep trap centers in Si and increased R_S.