一种具备谱学功能的扫描隧道显微镜实验装置设计与教学应用  

Design and application of a scanning tunneling microscope experimental apparatus with spectroscopic capabilities

作　　者：张靖伟 龚梓鑫 崔丹丹 冯海凤 郝维昌[1] 杜轶 ZHANG Jingwei;GONG Zixin;CUI Dandan;FENG Haifeng;HAO Weichang;DU Yi(School of Physics,Beihang University,Beijing 100191,China)

机构地区：[1]北京航空航天大学物理学院,北京100191

出　　处：《实验技术与管理》2024年第6期151-156,共6页Experimental Technology and Management

基　　金：北京航空航天大学2023年教育教学改革项目(北航教字[2016]12号);北京航空航天大学高水平学生科技创新团队(北航学字[2023]20号)。

摘　　要：该文研制了一种具备谱学功能的扫描隧道显微镜实验教学装置。装置采用紧凑的对称式结构设计和高刚性材料,具有漂移小、噪声低的优点,结合减震隔音设计,能够在课堂环境下稳定实现对多种材料表面的原子分辨成像。隧道电流的一阶微分谱直接反映了样品表面的电子态密度信息,可以帮助学生理解隧道电流信号。该装置集成了锁相放大功能,可以实现隧道电流-偏压谱及其一阶微分谱的测量,拓展了扫描探针显微实验的教学内容和教学深度。[Objective]Scanning tunneling microscopy(STM)is a pivotal method for achieving atomic-resolution imaging of material surfaces and is widely applied in the instructional context of physics experiments.Beyond imaging,STM facilitates spectroscopic analysis.Specifically,examining the first order differential spectrum of the tunneling current directly revealed the density of the electronic states on the sample surface.This detection significantly enhances the understanding of tunneling phenomena,thus bridging theoretical teaching and cutting edge research.However,the high stability required for tunneling spectra measurements limits their use in teaching experiments.[Methods]This paper introduces an innovative scanning tunneling microscope designed specifically for educational purposes that exhibits spectroscopic capabilities.The proposed apparatus combines a mechanical and control system to achieve ideal performance in a desktop system.The scan head,which is the central part of the mechanical system,features a compact,highly rigid design that uses hard materials such as titanium,alumina,and sapphire to minimize the size without sacrificing strength.A spring suspension damping system was used to further minimize the influence of environmental vibrations,while symmetrical piezoelectric stepper motors and tube scanners in the scan head mitigate thermal drift.The small size of the scan head and the use of high hardness materials also contributed to suppressing thermal drift.The scan head is canopied by a metal and glass cover to shield it from electromagnetic noise and sound waves.The control system includes a preamplifier,signal input and output modules,a voltage amplification module,and a microprocessor.Spectroscopic measurements were enabled by an AC signal generator and a lock in amplifier module.During first order differential spectrum measurements,a 10 mV 933 Hz AC signal supplements the DC bias,with lock-in modules extracting and amplifying the 933 Hz signal from the tunneling current.[Results]The STM system’s ex

关 键 词：扫描隧道显微镜 扫描隧道谱 近代物理实验 

分 类 号：O469[理学—凝聚态物理]