Diamond membrane production: The critical role of radicals in the non-contact electrochemical etching of sp2 carbon
Diamond membrane production: The critical role of radicals in the non-contact electrochemical etching of sp2 carbon
复制标题
金刚石膜生产：自由基在 sp2 碳非接触电化学蚀刻中的关键作用
DOI：
10.1016/j.carbon.2021.09.054
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发表时间：
2021
期刊：
影响因子：
10.9
通讯作者：
Tully J
中科院分区：
文献类型：
--
作者：
Tully J
亚微米单晶金刚石膜对于下一代光学、量子和电子器件应用具有巨大的重要性。电化学蚀刻已被证明是生产这种膜的关键步骤。蚀刻是用来选择性地去除一个非常薄的层次表面sp2碳，通过离子注入大块金刚石，释放金刚石膜。由于纳米尺寸，蚀刻通常在低电导率溶液（双极布置）中使用非接触电化学进行，这虽然有效，但导致极慢的蚀刻速率。本文提出了一种新的非接触式电化学腐蚀方法，该方法使用高电导率、高浓度、完全离解的水溶液电解液。仔细选择的电解质阴离子的结果在sp2碳蚀刻速率的显着改善。特别是，我们发现，与我们使用当前最先进的解决方案和方法进行的测量相比，氯化物和硫酸盐电解质显着提高了蚀刻速率（硫酸盐高达40倍）。电子顺磁共振实验，记录后，电极电位已经关闭，揭示了相当大的羟基自由基浓度的时间尺度> 107长于其寿命（≤μs）。这些测量突出了电化学引发的，溶液化学自由基生成和再生途径在高浓度硫酸盐和氯化物溶液中的纳米蚀刻应用的重要性。
Sub-micrometre single crystal diamond membranes are of huge importance for next generation optical, quantum and electronic device applications. Electrochemical etching has proven a critical step in the production of such membranes. Etching is used to selectively remove a very thin layer of sub-surface sp2carbon, prepared by ion implantation in bulk diamond, releasing the diamond membrane. Due to the nanosized dimensions, etching is typically carried out using non-contact electrochemistry in low conductivity solutions (bipolar arrangement) which whilst effective, results in extremely slow etch rates. In this work, a new method of non-contact electrochemical etching is presented which uses high conductivity, high concentration, fully dissociated aqueous electrolytes. Careful choice of the electrolyte anion results in significant improvements in the sp2carbon etch rate. In particular, we show both chloride and sulfate electrolytes increase etch rates significantly (up to × 40 for sulfate) compared to our measurements using the current state-of-the-art solutions and methodologies. Electron paramagnetic resonance experiments, recorded after the electrode potential has been switched off, reveal sizeable hydroxyl radical concentrations at timescales > 107longer than their lifetime (≤μs). These measurements highlight the importance of electrochemically initiated, solution chemistry radical generation and regeneration pathways in high concentration sulfate and chloride solutions for nano-etching applications.