Tip-shape investigation of a Au-Si alloy liquid metal ion source using a high voltage transmission electron microscope

Abstract

The tip shape of a Au-Si liquid-metal ion source in terms of its dependence on the total ion emission current has been investigated in situ in the Halle 1 MeV electron microscope. Within the emission current range 7-90 mu A there is a linear dependence of the cone half-angle a and the length I of the jet-like protrusion on the increased emission current. The jet-like protrusion at the Taylor cone vertex was not so pronounced as has been observed in the cases of elementary liquid-metal ion sources. No spatial shifts of the Taylor cone are seen during the experiments. In contrast to elementary liquid-metal ion sources, there is no indication of 'Faraday droplets' being emitted from the surroundings of the Taylor cone.

In situ observation of the tip shape of AuGe liquid alloy ion sources using a high voltage transmission electron microscope

“…A similar behavior of ␣ with increasing current can be seen for AuSi15 and CoGe 19 LAIS FIG. The slope of the curve changes at a current of 20 A from Ϫ0.28 to Ϫ0.045 deg/A.…”

“…There is a great effort to establish a theoretical model of these sources in order to understand the particle emission processes involved. The experimental results obtained with AuSi, 15 Ga, 16 In, 17 Sn, 18 and CoGe 19 ion sources gave evidence for a material dependence of the tip shape. [12][13][14] Therefore we have started a systematic in situ tip shape investigation of pure metal and alloy LMIS in the 1 MeV TEM at the Max-Planck-Institut in Halle.…”

“…[8][9][10][11] However, only in a few cases an operating LMIS has been observed in situ in a high-voltage transmission electron microscope ͑HVTEM͒. The investigations of the AuSi LAIS 15 have shown a completely different behavior compared with pure metal LMIS. The experimental results obtained with AuSi, 15 Ga, 16 In, 17 Sn, 18 and CoGe 19 ion sources gave evidence for a material dependence of the tip shape.…”

In situ observation of the tip shape of Co–Ge liquid alloy ion sources in a high-voltage transmission electron microscope

“…Therefore Driesel et al observed Au-Si, 3 and Au-Ge LAISs 4 in operation in a 1 MeV scanning electron microscope. 1 and 2͒.…”

“…1 and 2͒. 3 Transmission electron microscopy ͑TEM͒ investigations on Ga, 5,6 In, 7 and Sn liquid metal ion sources ͑LMIS͒ 8 during ion emission facilitated the better understanding of the ion and microdroplet emission process from LMISs in a large range of ion current. Therefore Driesel et al observed Au-Si, 3 and Au-Ge LAISs 4 in operation in a 1 MeV scanning electron microscope.…”