n型半导体硅电极表面Au的电化学成核机理

Electrochemical Nucleation of Au on n-Type Semiconductor Silicon Electrode Surface

在成功实现半导体硅表面电沉积致密金膜的柠檬酸盐镀金实际应用体系中,运用循环伏安和电位阶跃法研究了Au在n型Si(111)电极表面的电沉积过程和成核机理.结果表明,在该体系中,Au在Si表面呈现不可逆电极过程,成核过电位达到250 m V;根据Cottrell方程求得扩散系数D=(1.81±0.14)×10–4 cm2 s–1;运用Scharifker-Hills(SH)理论模型对比分析拟合实验结果,表明Au在n型Si表面遵循扩散控制下的三维连续成核机理;通过扫描电子显微镜观察Au初期成核、生长形貌,进一步证实了Au的三维连续成核机制,并讨论了阶跃电位和阶跃时间对Au核形貌和密度的影响.

Cyclic voltammetry and chronoamperometry have been used to investigate the mechanism of gold electrodeposition on the n-Si（111） electrode surface from a citrate bath, which had successfully applied to directly electroplate a dense gold film on the silicon surface. The results show that Au electrodeposition on the n-type silicon surface is an irreversible process, and the nucleation overpotential reaches 250 m V. According to Cottrell equation, the diffusion coefficient（D） is calculated to be（1.81 ± 0.14） × 10^-4 cm^2 s^-1. The Scharifker-Hills（SH） model was used to analyze the experimental data. Agreement between the fitting curves and the theoretical curves confirms that the nucleation process of Au electrodeposition on the n-type silicon surface follows the progressive nucleation mechanism with three-dimensional growth under diffusion control.To further confirm the progressive nucleation mechanism, scanning electron microscopy（SEM） was used to observe the nucleation and growth of Au deposits at the initial stage of electrodeposition. The SEM results show that the morphology and density of the Au deposits are affected by the electrochemical deposition potential and time.