利用掃描式電子穿隧顯微鏡探討添加劑對於銅沉積於金(111)的影響

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题名:	利用掃描式電子穿隧顯微鏡探討添加劑對於銅沉積於金(111)的影響
作者:	莊竣雅;Chuang,Chun-Ya
贡献者:	化學學系
关键词:	銅沉積;掃描式電子穿隧顯微鏡;金(111);添加劑;PEG;SPS;氯離子;分子修飾;加速劑;抑制劑
日期:	2016-08-15
上传时间:	2016-10-13 12:47:10 (UTC+8)
出版者:	國立中央大學
摘要:	本研究利用循環伏安法(CV)和掃描式電子穿隧顯微鏡(STM)探討氯離子、聚二硫二丙烷磺酸鹽(SPS)及聚乙二醇(PEG)對於銅沉積在金(111)上的影響。首先，對銅沉積於氯離子修飾金(111)上進行觀察，一般而言，氯離子對於銅的還原沉積為加速反應，但是當銅離子的濃度低於0.1mM 時，在溶液中加入少量的氯離子並不會加速銅的沉積速度，反而有抑制的效果；氯離子濃度過高時，對銅沉積也有抑制的效果。在0.1M 硫酸電解液中含有0.1mM 銅離子與0.1mM 氯離子時，利用改變不同的電位來影響銅沉積的形貌，發現若是直接將電位從0.5V 調整至-0.4V 時，和慢慢將電位往負調整至銅沉積電位使銅沉積的方法相比，銅沉積的方式主要以2D 方向成長。在SPS 對銅沉積的影響中，在電位為0.8V 時，發現將SPS 修飾在金(111)上會以(6 × 2√21)吸附在金表面上，在in situ STM 觀察到，經SPS 修飾金後加入銅離子進行銅還原沉積，將電位往負電位調整，銅會以3D 球狀方式沉積，而在添加實驗與氯離子共吸實驗中，也有相同的狀況。在PEG 對銅沉積的影響中，發現PEG 本身抑制銅的是因為本身的黏稠性使銅在溶液中不易擴散反應，使銅的沉積速度下降，在STM 觀察銅沉積的形貌，發現其與純銅沉積的形貌相似，將電位從0.5V 調整至-0.4V 時，可以發現銅從原本的3D 成長變成2D 成長，其面上為硫酸氫根以(√3 × √7)吸附在銅上。在PEG 與氯離子對銅沉積的影響中，由於PEG 會與氯離子形成一抑制膜，故將電位調整至0.1V 時，才會有過電位銅開始沉積，沉積電位較負，而沉積出的銅仍是以3D 方向成長，但將電位從0.5V 調整至-0.4V 時，銅會從台階下緣與平慢上開始沉積，主要以2D 方向成長，較先前的更平整，在其平面上可發現氯離子吸附在上面，發現有亮暗點之差，可能是有PEG 吸附在氯離子上所造成的。;In situ scanning tunneling microscopy (STM) and cyclic voltammetry (CV) have been used to investigate the effect of chloride ion, bis-3-sodiumsulfopropyl disulfide and polyethylene glycol on the electrodeposition of copper onto Au(111). Chloride ion can accelerate the reduction rate of copper ion, but this effect is insignificant when the copper concentration is lower than 0.1mM. Stepping the potential from 0.5 to -0.4 V to observe copper deposition in 0.1M Sulfuric acid and 0.1mM KCl with STM, which reveals 2D deposition mode of Cu on the ordered Au(111) electrode. This contrasts markedly with the 3D growth of Cu on Au(111) in a sulfate medium. The adsorption of chloride on Cu deposit is confirmed by STM imaging. The adsorbed Cl- adlayer increases the surface diffusion rate of Cu adatoms, helping them to transfer across the step barrier. SPS molecules are adsorbed in highly ordered array at 0.8 V, characterized as Au(111) - (6 × 2√21). In situ STM imaging reveals that Cu deposition grows in 3D in 0.1mM SPS, which is proposed to result from slow surface diffusion rate of Cu adatoms likely capped by segregated SPS molecules. However, it is intriguing that it is bisulfate anions structure, not the SPS, imaged by STM. When Cu deposit is stripped off, STM images a defected adlayer of SPS. The effect of PEG on Cu deposition on Au(111) is always suppressing, regardless of the presence of Cl-, which results from PEG’s high viscosity and slow-down of Cu2+ diffusion rate. STM imaging reveals rough Cu deposit when the potential is made negatively in steps in the presence of PEG6000 in the sulfate media. By contrast, abrupt adjusting from 0.5 to -0.4 V in the same medium, the copper film grows laterally, yielding a Cu smooth film on which a highly ordered bisulfate adlayer characterized as (√3 × √7) is imaged. Copper deposition in the presence of PEG and Cl yielded different processes and film morphology. The synergistic effect of PEG and Cl- indeed suppresses Cu deposition, as evidenced by the negative shift of the onset potential of copper deposition. STM imaging shows that Cu deposit grows in 3D when the potential is gradually made negative. By contrast, switching the potential abruptly from 0.5 to -0.4 V, Cu deposit nucleated at steps and on terraces, followed by lateral growth and coalescence of Cu islands at the latter stage.
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