Study on Electrochemical and Magnetic Properties of CoNi Alloy Coating Electrodeposited on Semiconductor Silicon

Abstract

The Co-Ni coating on the surface of semiconductor silicon commonly used for computer fields is prepared by plating using solutions containing different concentrations of cobalt sulfate. The influence of cobalt ions on the electrochemical and magnetic properties of Co-Ni coating is investigated to reveal the internal relationship of magnetic property, surface morphology and microstructure. The electrodeposition of cobalt is a diffusion controlled instantaneous nucleation while the electrodeposition of nickel belongs to an electrochemical controlled continuous nucleation. Increasing the concentration of cobalt sulfate in the plating solution from 5 g/L to 20 g/L is beneficial to increase the cobalt content and thickness, refine the particle size and reduce the surface roughness of Co-Ni coating, so as to increase the magnetic property. However, when the cobalt sulfate in the plating solution is 40 g/L, higher concentration of cobalt ions makes a large number of cobalt hydroxide and oxide adsorbed on the cathode surface resulting in poor magnetic property. The Co-Ni coating electrodeposited on the condition of 30 g/L cobalt sulfate has the best magnetic property with 314.64 Oe coercivity and 102.50 emu/g saturation magnetization.