## 2 Materials and Methods
### Platinum Carbon Composite  
Deposition by FIB/FEB through a Pt precursor is one of the most common variants among a variety of other available material composites with aluminum (Al), gold (Au), tungsten (W), or palladium (Pd), as examples. This investigation is based on the use of a metal-organic precursor material, MeCpPtMe3. In the metal-organic composite, the metallic components are present in an amorphous carbon matrix after deposition. This result has been widely investigated and can be confirmed by previous studies [20; 21; 22; 23; 24; 25; 26; 27; 28]. Therefore, compared to bulk Pt, the deposited material can be described as a metal highly contaminated by amorphous carbon impurities. Moreover, [PERSON] et al. [25] and [PERSON] et al. [26] give a comprehensive overview about processing with focused beam induced deposition (FBID) and the difference in technology between FIBID and FEBID. [PERSON] et al. [21] especially show the bonding structure of the FBID carbon matrix by Raman spectroscopy. The results show a diamond-like amorphous carbon (DLC) based on a sp2 bonding structure corresponding to graphite and sp3 bonding structure corresponding to diamond. The huge amount of high ohmic DLC leads to a high electric material resistance. The study of the resistance of PtC and the comparison to bulk Pt has great importance in some publications. Thus, it is deeply investigated and considered from different perspectives how large the resistance is in general and where the dependencies are regarding deposition parameters [5; 20; 28; 29; 30; 31], temperature [23; 28; 32], technology (FIB/FEB) [28; 30] or material thickness [19; 23]. [PERSON] et al. [31] presented a resistivity dependence on the chosen ion current and measured the lowest resistivity of the deposited nanowires at the highest ion current of 222 pA. Previous studies show different values for the resistivity of FIBID and FEBID Pt, but can be adopted as 1-2 orders of magnitude higher for FIBID Pt, and 4-5 orders for FEBID Pt than the resistivity of bulk Pt [19; 23; 28; 31]. The tunneling effect is primarily used in a scanning tunneling microscope (STM) for commercial purposes. Therefore, highly conductive tips are used, and contamination or oxidation is prevented by imaging under vacuum conditions. The first requirement for a high-resolution STM analysis is a pure metal tip with low resistance. In the configuration of a well conductive tip and probe, tunneling currents of up to 100 nA can be expected. Since high ohmic parts of the tunneling tip prevent electron tunneling from one electrode to another, the nanostructure of the PtC composite, particularly its edge area, needs to be investigated to determine the suitability of the tunneling mechanism. However, the conduction mechanism of metal-organic or granular materials is based on intergrain tunneling between the metallic components [16; 17; 18; 19; 20]. [PERSON] et al. [33] show the realization of a strain sensor by bending a Pt nanowire and, therefore, a great change in the material inherent resistance through the exponential dependence of the distance between the metallic grains and the tunneling current. This leads to a resistivity dependence on the size and distance of the metallic components to each other. For a tunneling application through a vacuum gap, this is a significant aspect because if the Pt grains are located directly at the edge of the tip, a tunneling current can occur. This is one of the main aspects of this work, as the application of PtC tips allows tunneling application through a vacuum gap by suitable location and distribution of Pt grains. Examination by HRTEM represents the most considerable analysis for this purpose since the microstructure of the tip can be imaged on the nano- and picometer scale. Due to the high flexibility of the FIB, the integration of sharp tips enables a wide range of tunneling applications for sensors based on movable parts such as accelerometers or pressure sensors.