This work presents a comprehensive investigation of Si/Ni/Cu metallization stacks, consisting of an electrodeposited nickel (Ni) layer deposited directly on the silicon substrate and a subsequent electrodeposited copper (Cu) layer serving as the conductive overlayer [1]. The study focuses on the potential of this bilayer architecture for the development of low-resistance metallic contacts for silicon photovoltaic applications. A combination of structural, morphological, thickness, electrical, and interfacial characterization techniques was employed to establish the relationship between the deposition conditions and the resulting properties of the Ni/Cu metallization. The electrical properties of the deposited layers were evaluated using four-point probe and Hall-effect measurements, while scanning electron microscopy (SEM) was used to investigate the surface morphology and microstructural features of the Ni/Cu stack. The film exhibits a compact structure with a granular texture, indicating a relatively homogeneous nucleation and growth over the entire area. The top of Cu layer were coral-like and consisted of small cauliflower-like agglomerates with an estimated of the average size about 225nm and 275nm. The quality of the metal/semiconductor contact was assessed using the transmission line method (TLM) that reveals significantly lower contact resistance for Cu (33.04nΩ) compared to Ni (3.26mΩ), emphasizing the superior electrical coupling at the Cu–Si interface. Electrochemical impedance spectroscopy (EIS) was additionally employed to investigate interfacial charge-transfer processes and the electrical behavior of the metal/semiconductor interface, with the impedance response interpreted using an equivalent electrical circuit model. The observed variation in charge transfer resistance (R_ct​) in double-layer Ni/Cu systems as a function of annealing provides critical insights into the interfacial and microstructural stability of these bilayer structures.

The combined characterization results demonstrate that the deposition conditions significantly affect the morphology, electrical conductivity and interfacial properties of the Si/Ni/Cu bilayer structure. In particular, the Ni interfacial layer plays an important role in establishing the electrical contact with silicon, while the Cu overlayer contributes to the reduction of the series resistance and provides an efficient conductive path. The correlation between the morphological characteristics of the Ni/Cu stack and its contact resistance provides valuable insight into the optimization of electrodeposited metallization for silicon solar cells. Overall, the investigated Si/Ni/Cu architecture demonstrates promising characteristics for low-resistance photovoltaic contacts.