自製掃描式穿隧電子顯微鏡之進針系統自動化與改良

Design of automatic tip approaching system for homemade scanning tunneling microscope

余柏韋(Po-Wei Yu)

指導教授 ： 簡紋濱

國立交通大學/理學院/電子物理系所/碩士(2020年)

摘要

本研究發展自製掃描式穿隧電子顯微鏡 (Scanning tunneling microscope, STM)，其優點有體積小、攜帶方便，且在室溫環境下即能進行STM掃描，可快速觀察材料表面形貌與分析材料的穿隧能譜 (Scan tunneling spectroscopy, STS)。此次實驗主要發展此STM所需之進針系統，從每步微米尺度精進到奈米尺度，實驗中我們利用步進馬達、精密螺絲與齒輪結合，再搭配幾何結構設計，精進進針系統可在2分鐘內驅動探針接近樣品表面。過去實驗室使用手動進針STM系統，此奈米步伐自動進針STM機台操作更容易，並可縮短實驗時間與降低STM探針損壞機率，從而提高實驗的品質。此新設計之機，用來觀察對鍍金的光碟樣品，其STM影像可以觀察到~8.8 nm水平尺度的金顆粒，又使用此機台來觀察石墨 (Highly ordered pyrolytic graphite, HOPG)表面，可測量到石墨表面單元子層~0.3 nm的厚度。實驗結果證實，本研究開發的奈米級自動進針STM系統，其水平解析度為奈米等級，垂直解析度為原子等級。此外，使用此STM系統測量HOPG表面的STS，其能態密度與文獻紀載一致。

關鍵字

掃描式穿隧電子顯微鏡 ； 掃描穿隧能譜 ； 自動化 ； 進針

並列摘要

In this thesis, we present the development of an automatic approaching system for a portable, light, and homemade scanning tunneling microscope (STM). We also demonstrate its ability to observe surface morphology and to measure scanning tunneling spectroscopy (STS) in ambient conditions. The average approach time of the automatic tip approaching system help to reduce the approaching time down to two minutes. The approaching system consists of well-designed machine structure integrated with a motor, a high-precision screw and several gears to realize the finest resolution of ~1 nm per step. Comparing to previous manual aproaching system, the operation is dramatically easier so it reduces the tip damage problems and time wasting. It of course improves the quality to do experiments by using STM. To demonstrate the capabilities of our new designed machine, we observe gold particles of ~8.8nm on Au-coated DVD discs, and the single layer thickness of 0.3 nm on HOPG surface. These results show that the lateral resolution of homemade STM achieves nanometer scale and the vertical resolution achieves an atomic scale. Additionally, we also carry out the STS measurement on the HOPG surface and confirm that the results are consistent with previous reports in the literature.

並列關鍵字

Scanning Tunneling Microscope ； Scanning tunneling spectroscopy ； Automation ； Tip approaching

參考文獻

[1] G. Binning, H. Rohrer, Ch. Gerber, and E. Weibel, Appl. Phys. Lett. 40, 178 (1981).

[2] C. J. Chen, Introduction to Scanning Tunneling Microscopy (Oxford University Press, New York, 1993).

[3] M. Wilms, M. Schmidt, G. Bermes, and K. Wandelt, Rev. Sci. Instrum. 69, 2696 (1998).

[4] F. J. Giessibl, Appl. Phys. Lett. 73, 3956 (1998).

[5] K. Karrai and R. D. Grober, Appl. Phys. Lett. 66, 1842 (1995).