1 R. Lõhmus, 2 D. Erts, 1 A. Lõhmus, 3 K. Svensson, 3 Y. Jompol, 3 H. Olin
1 Institute of Physics, University of Tartu, 142 Riia Str., 51014 Tartu, Estonia, rynno@fi.tartu.ee
, FAX: 372-383033.
2 Institute of Chemical Physics, University of Latvia, LV-1586 Riga, Latvia
3 Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
Abstract . STM and AFM combined with a transmission electron microscope (TEM) are effective tools for the direct investigations of the structure, electronic properties, and interactions on the atomic and nanometer scale. We present 2 designs of TEM-SPM, the coarse approach of the tip is being performed by a stepper motor and/or single-directional inertial slider, and by a new type of 3directional inertial slider, respectively. Some new experimental results are included to demonstrate capabilities of TEM-SPM.
1. Introduction. A scanning probe microscope (SPM) inside a transmission electron microscope is an attractive combined tool for the direct investigations of the structure, electronic properties, and interactions on the atomic scale. TEM-STM has proven to be useful [1-7], for example, in creation of atomic-sized metallic wires and simultaneous conductance measurements [3], gold contact area observations [4], carbon nanotube studies [5], and point contact experiments [6]. Recently TEM-
AFM was invented and used for in situ studies of force interactions [7,8]. Several constructions of
TEM-STM are presented in the literature. Geared electrical motors are commonly used for the coarse approach [2-6]. Micro-machined [2] TEM-STM and 3-directional inertial slider [7] were used in some experiments.
Here we present 2 TEM-SPM designs with different coarse approach systems and discuss their advantages. The first one is based on stepper motor and/or or single-directional inertial slider
(Fig.1), while the second design uses a new type ball-based three-directional inertial slider (Fig. 2).
2. Experimental. The TEM-SPMs were inserted into a field emission gun TEM (Philips CM200
Super TWIN FEG microscope). Inside the TEM we prepared the sample locally by pressing the tip hard into the sample or by pulling a notched wire. The AFM cantilever (force constant 0.4 N/m) and tips were coated with 5 nm Cr adhesive layer and with 15 nm Au film. The current signal was monitored on a digital oscilloscope simultaneously with the video TEM images.
3. Designs. Fig 1 shows a TEM-SPM based on a stepper motor and 1-dimensional inertial slider
That construction enables clean tip surfaces to be prepared by breaking notched wires inside the
TEM with stepper motor. Then the clutch is released by turning the stepper motor back.

4 5
8
6
7
1 2 3
Fig. 1. Stepper motor based TEM-SPM (Not to scale): 1-Shifting rod by stepper motor, 2inertial slider, 3-graphite rings, 4-clutch, 5piezo tube, 6-preadjustment ball, 7-stop screw,
8-electron beam.
5
3
4
Fig. 2. Ball-type of the inertial slider: 1-tip holder, 2-sapphire ball, 3-sliding rods,
4-counter weight, 5-piezo tube.
2
1
The clutch enables to decrease the mechanical loop. The coarse approach can be realised by singledirectional inertial slider in this design as well. Friction pair of the slider was formed by titanium rod sliding against 2 graphite surfaces at the ends of the piezotube. A saw-shape voltage was applied to the piezotube to move the titanium rod.
The main advantage of the three-directional inertial slider is an easy and reliable adjustment of the tips inside TEM. New construction of the slider (Fig. 2) is based on inertial movement of the head over the sapphire ball, and differs principally from the construction suggested in [8]. A sawshape voltage is applied to different piezotube segments and realises the movement of the tip holder
(2) in all directions. The fine adjustment of the tip in all constructions is realised by applying voltage on piezotube.
An example of measurements with the TEM-STM is the jump-to-contact between two gold tips (Fig. 3 a-b). The jump occurred at a distance of about 1 nm, which was two times larger than the value obtained by molecular dynamics simulations by Landman et al. [9].
Fig. 3 (a-b) TEM-STM images of the jump to contact between two gold tips.
Fig. 4 (a-b) Contact between an AFM tip (right) and a gold sample (left),
(c) The force curve with steps (1) and the corresponding contact area (2); the points marked a and b corresponds to TEM images in Fig 4a) and 4b).
The TEM-AFM was simply made by replacing the STM tip with an AFM tip. The tip displacement was measured directly from the TEM images, and together with the known spring constant of the cantilever, the force acting on the tip was calculated. An example of TEM-AFM

measurement is shown in Fig 3c) and d). Several contacts were broken during the retraction, which shows up as jumps in the force curve (1) (Fig. 3 e). The area of the contacts (2) was also measured simultaneously (Fig. 3 e).
0
-2 0 2 4 6 8 10 12
0
-50 c
-100 a b c d
Fig. 3 (a-b) TEM-STM images of the jump to contact between two gold tips.
Sample displacement, nm e d
-1.5
-3
-4.5
(c-d) Contact between an AFM tip (right) and a gold sample (left),
(e) The force curve with steps (1) and the corresponding contact area (2); the points marked c and d corresponds to TEM images in Fig 3c) and d).
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D. Erts, A Lõhmus, R. Lõhmus, H. Olin, Appl. Phys. A
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