JPH03223606A - Tunnel-current detecting apparatus - Google Patents

Abstract

PURPOSE:To detect and control a stable tunnel current not only from a semiconductor but also from the surface of a metal sample and to make it possible to observe the image of an atom directly by changing the material of a tunnel- current detecting apparatus from metal to graphite. CONSTITUTION:In an apparatus utilizing the tunnel effects of a scanning type tunnel microscope and the like, a probe supporting substrate 15 is attached in a driving part 16 which can be driven in the horizontal direction and in the vertical direction. A probe 11 made of graphite (e.g. constituted of the components of carbon fiber and the cores of penciles and the like) is attached to the substrate 15. When the material of the probe is changed from metal to the graphite, a stable tunnel current can be detected and controlled not only from a semiconductor but also from the surface of a metal sample. Furthermore, the current can be controlled even in atmosphere. The surface of the thin film of gold in the atmosphere is observed, and the image of the atom can be directly obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a tunneling current detection device such as a scanning tunneling microscope that utilizes the tunneling effect.

(Conventional technology) FIG. 2 shows a conventional device.

In scanning tunneling microscopes, scanning tunneling spectrometers, ultra-roughness meters, etc., in order to observe the shape of material surfaces and measure physical properties, the probe is brought close to the sample surface at a distance of 5 to 50 people, and an appropriate bias is applied. Utilizes the tunnel effect produced by applying voltage. Here, the tunnel effect refers to a physical phenomenon in which a tunnel current flows depending on the distance between the probe and the sample, the bias voltage, and the electronic states of the probe and the sample.

Conventionally, at the tip of the unit for tunnel current detection,
As shown in FIG. 2, probes made of metal materials such as platinum iridium and tungsten have been used.

By using such a device, it was possible to stably detect tunnel current from the surface of a semiconductor.

(To be solved by the invention: lllff1) However, in the conventional apparatus described above, when trying to detect a tunnel current from the surface of a metal sample, there are problems such as that the tunnel current is not stable. Therefore, it has been extremely difficult to detect and control tunneling current from the surface of metal samples.

The present invention aims to provide a device that solves these problems.

(Means for Solving the Problems) A tunnel current detection device according to the present invention is a device that utilizes a tunnel effect, such as a scanning tunneling microscope, and includes a drive section 16 that can scan in the horizontal and vertical directions, and a drive section 16 that can scan in the horizontal and vertical directions. An attached probe support base 15 and a probe 11 made of graphite attached to the probe support base 15.
, a bias voltage power supply 12 that can apply an appropriate bias voltage between the probe and the sample, and an ammeter 13 that detects the tunnel current flowing between the probe and the sample. .

(Function) In the device of the present invention, by changing the material of the probe of the tunneling current detection device from metal to graphite, stable tunneling current can be detected and controlled not only from the surface of semiconductors but also from the surface of metal samples. Atomic images on the surface can also be directly observed.

(Example) An embodiment of the invention is shown in FIGS. 1 and 3.

FIG. 1 shows the configuration of an embodiment of the present invention. 1 in Figure 1
1 is a probe made of graphite (e.g. carbon fiber,
(such as those composed of the core components of pencils, etc.). 12 is a power source electrically connected to the probe for applying a bias voltage to the probe, and 15 is a base for supporting the probe.

FIG. 3 shows an atomic image obtained when the surface of a thin film of gold (Au) (vacuum deposited in the form of glass) was observed in the atmosphere using an apparatus according to an embodiment of the present invention.

No observations have been made in the atmosphere using conventional equipment.

This is because in the atmosphere, due to the effects of impurities on the surface, atmospheric fluctuations, etc., when moving (scanning) the probe, the tunneling current may or may not flow excessively.
This is because the tunnel current could not be controlled.

With the probe of the device of the present invention, it was possible to control the current even in the atmosphere, and we were able to obtain the image shown in Figure 3.

Figure 4 shows the “conventional tunnel current detection device” published in the paper by Y. Kuk et al. (1988).
This is a surface atomic image of gold (Au) obtained by scanning tunneling microscopy (STM) using . As far as we can see in Figure 4, the atomic image obtained in this example (Figure 3) appears to be on the same level as the atomic image obtained in this example (Figure 3). ), which are very close to ideal conditions.

Although the surface atomic images of gold (Au) published in other papers were measured under ideal conditions, the images obtained were only comparable to those shown in Figure 4. Furthermore, atomic images measured under adverse conditions in the atmosphere as in this example have not been published.

Scanning tunneling microscope using the present invention 1! If measurement is performed under ideal conditions using STM, an even clearer image of Au surface atoms can be obtained.

[Effects of the Invention] Since the present invention is configured as described above, it has the following effects.

(1) Since the probe is made of graphite, it is possible to accurately detect and control stable tunneling current from the metal surface, which has been difficult to observe in the past.

(2) Therefore, an atomic image of the surface of a metal sample can also be obtained.

(3) It is possible to accurately detect and control stable tunnel current even in semiconductors.

[Brief explanation of drawings]

Fig. 1 shows an embodiment of the present invention, Fig. 2 shows a conventional device, and Fig. 3 shows gold (Au) obtained in the atmosphere by the device of the present invention.
) photo of surface atomic image, 11... probe made of graphite, 12°22.
...Bias voltage power supply, 13.23...Ammeter, 1
4.24... Sample, 15.25... Probe support base, 16.26... x, y, z direction drive device, 21...
- A probe made of metal.

Claims (1)

[Claims] In a device that utilizes a tunnel effect such as a scanning tunneling microscope, a drive unit 16 that can scan in the horizontal and vertical directions.
and a probe support base 15 attached to the drive unit;
A probe 11 made of graphite attached to the probe support base, a bias voltage power source 12 capable of applying an appropriate bias voltage between the probe and the sample, and a gap between the probe and the sample. ammeter 13 that detects the tunnel current flowing through the
A tunnel current detection device comprising: