Fabrication Ohmic Contact of Ni/Cu Structure on Polycrystalline Silicon Via Electrochemical Method used in Solar Cells

In this paper, a low-cost Ni/Cu structure as an ohmic contact was fabricated on Polycrystalline n+Si Via electrochemical method by the application of an ultrasonic system and the electrical resistivity of the contact was optimized. After electroplating of Ni in watts bath for 10, 20 and 40 min, an electroplated copper layer was deppsited on Ni film in order to reduce the sheet and contact resistance by using an ultrasonic system one can obtain a film with the lower surface roughness and the higher quality. The electrical resistivity of the electroplated Ni/Cu was investigated for vacuum annealing at various temperatures. Post treatments of the coated Ni improved the crystalline structure of the electroplated layer. Contact resistance of the Ni/Cu structure on an n+Si was measured using the Transmission Line Model (TLM) Method. An optimum specific contact resistance of 2.2×10-5 Ωcm2 was obtained for layers annealed at 400°C for 10 min. SEM, XRD, and EDX analyses were used to investigate the surface morphology, structure and composition of deposited films.