Influence of Tip Temperature on Field Evaporation in Atom Probe

Abstract

Recently, laser pulses on a three-dimensional atom probe have been used to trigger the field evaporation. The advantages of laser-pulse atom probes are high mass resolution and application to higher resistivity materials such as semiconductors. Most recent studies using laser pulses have indicated that the field evaporation of atoms occurred by a thermal pulsing mechanism. In this study, we analyzed the metal specimens, tungsten, nickel and aluminum, by using the hand-made 3DAP in our laboratory, and verified the mechanism of field evaporation by laser pulses. From the results, the spatial resolution might be extremely better at lower tip temperature. The difference of mass resolution between the laser-irradiated and shadow sides was observed and this might resulted from the difference of cooling duration in both sides. In the reconstruction calculation, the difference of curvature radii in the laser-irradiated and shadow sides was compensated and the spatial resolution was evaluated.

Study of the Ionization in a Field Ion Microscope Using Pulsed-Laser

“…In the APM with pulsed laser, the specimen temperature was reported to increase because of the irradiated pulsed laser [4]. In that case, a temperature gradient was generated at the parallel axis along the irradiation direction of the pulsed laser [5]. Furthermore, the required strength of the electric field for field evaporation was reduced by increasing the specimen temperature [6].…”

Alternate field evaporation by changing laser pulsing and voltage pulsing dynamically for atom probe analysis

“…Voltage pulse which has been used from the establishment of AP in the 1960s is going to be replaced by short pulsed laser with high repetition rate in the nanometer scale characterization of materials by 3‐dimensional AP (3D‐AP) . The criterion for choosing appropriate trigger method is not clear and under discussion because it is difficult to compare the result of 2 triggering methods applied on the same sample in atomic scale . The precise comparison of 2 triggering methods was proposed by the authors by applying voltage pulse and laser pulse alternately to the identical sample .…”

“…1,2 The criterion for choosing appropriate trigger method is not clear and under discussion because it is difficult to compare the result of 2 triggering methods applied on the same sample in atomic scale. [3][4][5] The precise comparison of 2 triggering methods was proposed by the authors by applying voltage pulse and laser pulse alternately to the identical sample. 6 The results of mass spectrometric composition and spatial information of desorbed ions reflected the mechanism of triggering field evaporation.…”

Investigation of Sample Deformation in Laser-Assisted Atom Probe Tomography

“…The mechanism through which the laser causes sample deformation is currently unclear and under debate; however, a reasonable assumption is that laser heating of the sample affects the shape. In laser-assisted APT, the sample temperature has been reported to increase under the influence of the irradiated pulsed laser [8], generating a temperature gradient at the axis parallel to the irradiation direction of the pulsed laser [9]. Because the strength of the electric field − 10 − for field evaporation decreases with increasing sample temperature [10], it is believed that the rates of field evaporation differ at the irradiated and shadow sides when the temperature gradient is generated.…”