Title:

Exploring the Effects of Tip Shapes on Tip-Sample Interactions for Scanning Tunneling Microscopy

Creating new technologies to advance our society and solve big problems requires scientists and engineers to find creative ways to utilize existing materials more efficiently, as well as explore promising new materials with desirable properties. Before new materials can be incorporated into future technologies, it is essential to understand their properties, behavior, benefits and limitations. Scanning tunneling microscopy (STM) is a robust imaging technique used to study the electronic properties and topography of materials on the atomic scale. It works by scanning a sharp metallic tip over a conductive sample. The shape of the tip and its interaction with the sample have a significant effect on images produced by STM. In this project, I studied the effect of tip shapes on STM images to better understand tip-sample interactions. An effect called tip induced band bending (TIBB), which occurs when imaging semiconductors, was of particular interest. Here, I present a two-step electrochemical etching process to fabricate Pt/Ir STM tips, including results of varying parameters like etching duration and voltage to optimize tip sharpness, uniformity and stability. I simulate the produced tips using SEMITIP and Finite Element Method Magnetics (FEMM) to predict the expected band bending and resulting STM image. Future work will use fabricated tips to image black phosphorous and compare to simulation results.

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