光电化学沉积提取半导体元素的基础理论---以碲为例

To address the problems for semiconductor elements extraction by traditional electrodeposition method such as low deposition rate, low current density, bad process stability and high energy consumption, a novel photoelectrochemical deposition method is proposed to extract the elemental semiconductor elements and its fundamentals and technology will be investigated via taking tellurium as an example in his project. Firstly, efforts will be devoted to revealing the characteristics of mass and charge transfer in the deposition processes via semiconductor/electrolyte energy level and structure analysis; then the equivalent circuit will be established to simulate and analyze the electrode processes based on the electrochemical impedance tests; besides, the relevant electrochemical behaviors will be explored using steady state polarization curve and cyclic voltammetry-electrochemical quartz crystal microbalance test; also, the nucleation and growth mechanism will be illustrated by the combination investigations of morphology and structure evolution of the deposited Te and chronoamperometry measurement. By the studying on effects of illumination characteristics and deposition paramaters on the key technical indexes and side reactions, the control mechanism of photoelectrochemical deposition of Te will be established, and optimal prototypes can be formed. This project is novel and can be regarded as the important extension of electrochemical extraction metallurgy. Its pioneering theoretical and technical results can be used in the Te metallurgical industry, and spread to other elemental semiconductors extraction, which will significantly promote the development of electrodeposition metallurgical technologies.

针对常规电沉积法提取半导体元素存在的沉积速率慢、电流密度低、工艺稳定性差和能耗高等不足，本项目提出采用光电化学沉积法提取半导体元素的新方法，并以碲为例开展光电化学沉积的基础理论和技术研究。项目将通过半导体/电解液能级结构分析，阐明沉积的传质传荷特征；采用电化学阻抗技术构建等效电路，实现电极过程的模拟和解析；采用稳态极化曲线和循环伏安-电化学石英晶体微天平联用技术探明沉积电化学行为，并结合碲的形貌的演变规律和计时安培分析，归纳形成与生长机制。通过明确光照特性和沉积参数对电沉积碲主要技术指标和副反应影响的规律及机制，建立光电化学沉积提取碲的过程调控机制，并形成工艺优化的技术原型。项目的成果具有开创性，是电化学提取冶金领域的新拓展，不仅可以直接应用于碲电沉积提取工业体系的强化与节能，而且其揭示的基本特征和规律还可为其他半导体元素的光电化学沉积提取提供指导，推动整个电沉积冶金技术的发展。

由于半导体元素导电性差等区别于金属元素的特性，传统的电沉积法在提取半导体元素时效率不高，存在沉积速率慢、电流密度低、工艺稳定性差和能耗高等问题。为解决这一问题，本项目充分利用半导体元素的光电特性，提出采用光电化学沉积法提取半导体元素，在碲-Te、碲化锌-ZnTe、及二氧化锰-MnO2的光电化学沉积探索中，开展了光电化学沉积的基础理论和技术研究，实现了半导体材料低成本、低能耗、无污染和高产能的冶金提取，并且深入研究了工业电解液中存在的杂质离子Co2+、Ni2+、Mg2+对电解MnO2的影响。项目取得的重要结果包括（1）揭示了光电化学沉积提取工艺对半导体材料（Te、ZnTe、MnO2）的提取影响；（2）基于多种电化学测试方法，揭示光照对反应体系中氧化还原过程影响并阐明了光电化学体系反应进程；（3）明确光照对半导体产物及性能的影响；（4）明晰了Co2+、Ni2+、Mg2+对电解MnO2对二氧化锰电化学行为及对电解二氧化锰的影响。相关研究结果证明采用光电化学沉积能够在一定程度上解决传统电沉积提取半导体元素所遇到的系列瓶颈，促进半导体元素冶金技术的进步。