Very Sharp Platinum Tips by Electrochemical Etching

4 Tip properties Martin Kupper 0830965Figure 4.3: The surface of two micropolished, unannealed tips. It is not possible tolocate any grain boundaries on the surface.4.2 Electrical propertiesBecause the tips are to be used for electrical measurements, the electrical propertiesof the tips have been studied. The resistivity between two tips is about 30 - 50 Ω, ifthe oxide layer has been removed. If there is an oxide layer, there is a bigger chanceof melting the tip than breaking through the oxide. More important though is thecontact to the sample. It was impossible to create such a contact. Fig.4.4 showns twoEBIC measurements of two PT/It tips in contact with a silicon sample. It can be seenthat the contact between the tip and the sample is not at the head of the tip. ThreeIV curves are shown in Fig.4.5.Figure 4.4: EBIC measurement of two Pt/Ir tips on a silicon sample. A separateEBIC measurement was made for each tip. For an unknown reason bothtips could not be measured at the particular time. For the correspondingIV curves see Fig.4.5.17