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扫描隧道显微镜是一种分辨率极高的表面研究仪器,针尖对其工作过程及图像质量有决定性的影响。本文针对目前针尖腐蚀成功率较低和不稳定的缺点,提出了一种新的电路。该设计改变了反应电流的测量机制,使实际反应电压在实验过程中保持稳定,同时为了得到更加尖锐的针尖,利用差分电路监控反应过程的电流变化,能够在反应结束的瞬间立刻切断电路,避免了过度反应使针尖变钝。最后,通过观察反应电压,阴极圆环位置,差分电路灵敏度以及电解液浓度对针尖质量的影响,给出了合适的反应参数,并且比较了差分电路和传统电流阈值监控法的优缺点。结果表明新电路在稳定性上有所提高,与电流阈值监控法相比,针尖质量更好,另外扫描隧道显微镜测试结果也表明针尖质量完全符合要求。
Scanning tunneling microscope is a high resolution surface research instrument, the tip of the work process and image quality has a decisive impact. In this paper, aiming at the shortcoming of low success rate of needle tip corrosion and instability, a new circuit is proposed. The design changes the measurement mechanism of the reaction current so that the actual reaction voltage remains stable during the experiment. In order to obtain a sharper tip, the differential circuit is used to monitor the change of the current in the reaction process, so that the circuit can be cut off immediately at the end of the reaction to avoid Excessive reaction blunt tip. Finally, by observing the influence of reaction voltage, cathode ring position, differential circuit sensitivity and electrolyte concentration on needle tip quality, the appropriate reaction parameters are given, and the advantages and disadvantages of differential circuit and traditional current threshold monitoring method are compared. The results show that the stability of the new circuit has improved, compared with the current threshold monitoring method, the tip quality is better, another scanning tunneling microscope test results also show that the tip quality fully meet the requirements.