In situ transmission-electron-microscope observation of electron-beam-deposited Pt field emitter under field emission and field evaporation

Abstract

A coherent-field emitter for electron-wave interference has been investigated in our study. So far, electron-wave interferences were observed from the Pt field emitter fabricated by electron-beam-induced deposition (EBID).1 It has been suggested that the electron-wave interference takes place by electrons emitted from individual adjacent emission sites within a Pt nanocrystal.2 It was, however, unclear whether the electron beams were emitted from a Pt nanocrystals, because Pt layers fabricated by EBID were the composites of Pt nanocrystals and amorphous carbon matrix. Furthermore, the resistivity of EB-deposited Pt nanowire was found to be quite high (1 Ωcm) and decreases by three orders of magnitude after annealing at 400° C.3,4 The grain size of Pt nanocrystals was also found to increase by annealing.5 In our experiment, the emission current of more than 10 μA can be obtained from an EB-deposited Pt field emitter, although the as-deposited Pt field emitter has quite high resistance. The structure of Pt field emitters might be varied due to the Joule heating during field emission. In addition, the possibility for the control of emission sites by field evaporation will be investigated in order to fabricate the coherent-field emitter for electron-wave interference in our future experiment. Therefore, the clarification of the structural changes in Pt field emitters under field emission and field evaporation are important in order to develop the coherent-field emitter utilizing EB-deposited Pt. In this study, the structural changes in the EB-deposited Pt field emitter under field emission and field evaporation were investigated by in situ transmission-electron-microscope (TEM) observation.