Study of electrical and morphological properties of AgInSe2 thin films grown by co-evaporation

AgInSe₂ (AlSe) thin films grown with chalcopyrite type tetragonal structure using a procedure based on the co-evaporation of their precursors in a two stage process, were electrically and morphologically characterized. The effect of the evaporated mass of Ag to evaporated mass of In (m_Ag/m_ln) ratio on the electrical and morphological properties as well as on the chemical composition was investigated through Hall voltage, AFM (Atomic Force Microscopy). Atomic force microscopy (AFM) measurements revealed that the AlSe films that we have grown, present average values of grain size ranging from 0.3 to 0.45 μm; however, this value increases when the m_Ag/m_ln ratio increase. It was also found that the resistivity of the AlSe films is strongly affected by both, the m_Ag/m_ln ratio and growth temperature, mainly due to changes of the carrier concentration. It was also found that the AgInSe₂ films present p-type conductivity, a high absorption coefficient (greater than 10⁴ cm^-1) and an energy band gap Eg of about 1.37 eV, indicating that this compound has good properties to perform as absorbent layer in thin film solar cells.