Cluster ion formation on electrode surface with high electric field

Abstract Ions evaporated from GaP and W tips were produced by pulsed-laser irradiation under applying d.c. high voltage. These were analysed using a combined-type atom-probe field ion microscope (FIM) with laser pulse operation and the usual high-voltage pulse operation. It was found that garium and tungsten were detected as atomic ions in the laser pulse mode similarly to the high-voltage pulse mode. The detected phosphorus formed more cluster ions. The obtained composition of GaP tips was Ga:P=1:1 at cryogenic temperature in a vacuum of better than 1×10 −8  Pa. We also clarified the influences of laser beam power density irradiated on the tip for field evaporation and formation of cluster ions.