Nanoparticle Manipulation with an AFM Probe

Scanning probe lithography (SPL) includes a variety of techniques which produce nanopatterns based on the interaction between an AFM probe and a substrate, Figure 1 shows an overview of possible techniques of scanning probe lithography. Here we focus on thermal SPL where a heated probe is used to remove or transform material of the substrate. Advantages such as the use under ambient conditions, large throughput even at high resolution, single step processing and the possibility of closed-loop lithography make scanning probe lithography very competitive in the field of nano-fabrication (1). In t-SPL the temperature at the apex is an important quantity in studying the behavior of different materials under fast exposure to heat. Due to heat losses and a limited heat transport from the heater to the apex, the temperature at the tip is not a priori known. To measure the temperature at a scale of <100 nm a small sensor with a low thermal mass is required. A suitable method is to use the temperature dependence of luminescent nanoparticles which are in direct contact with the tip apex. A challenging task is to pick up these particles from the substrate and attach them to the tip without surface functionalization to ensure a low thermal resistance between tip and nanoparticle. Additional energy from the probe is required to remove the particle from the substrate. Hence, the goal of this project was to find a procedure to attach diamond nanoparticles with NV centers onto the tip of a commercially available thermal scanning lithography probe (NanoFrazor). Preliminary tests with polystyrene beads with a diameter of 500 nm were conducted. Due to their larger size and bright fluorescence, manipulation with the thermal probe and respectively imaging with a confocal fluorescence microscope was facilitated. The experience gained from the large particles was used for the smaller diamond nanoparticles. It could be shown that scratching with the probe over previously localized, trapped nanodiamonds on a silicon substrate (see Figure 2) effectively removes the particles from the trap. Subsequent SEM imaging of the probes showed that in 10 out of 14 cases a particle or small cluster was attached to the tip. The location of the particles around the tip varied strongly both radially as well as in distance to the apex (see Figure 3). Whereas proximity to the apex increases the accuracy of future temperature measurements, it also limits the range of possible experiments by increasing the risk of detachment.

Zimmermann, Samuel Tobias
Brugger, Jürgen
May 11 2017

Note: The status of this file is: Involved Laboratories Only

 Record created 2018-07-05, last modified 2018-07-19

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