RF Reflection Scanning Tunneling Microscopy

Abstract

The invention provides a radio frequency reflection type scanning tunneling microscope. The radio frequency reflection type scanning tunneling microscope is provided with a probe which is relatively arranged in interval from one sample to be detected and is used for scanning the surface appearance of the sample to be detected. The radio frequency reflection type scanning tunneling microscope includes: a radio frequency scanning resonance circuit and a direction coupler, a radio frequency signal source and a radio frequency signal measuring system, wherein the radio frequency scanning resonance circuit includes an inductor, a capacitor, a resistor and a tunneling resistor; the capacitor, the resistor and the tunneling resistor are connected with one end of the inductor in parallel; the tunneling resistor is formed between the probe and the sample to be detected; the direction coupler is coupled with the other end of the inductor; the radio frequency signal generates a radio frequency signal and outputs the radio frequency signal to the radio frequency signal source of the radio frequency scanning resonance circuit through the direction coupler; and the radio frequency measuring system receives one radio frequency reflection signal sent from the radio frequency scanning resonance circuit through the direction coupler, and according to the radio frequency reflection signal performs feedback control of the probe, and generates a scanning result related with the surface appearance of the sample to be detected.

Description

technical field [0001] The invention relates to a tunneling microscope, in particular to a radio frequency reflection scanning tunneling microscope. Background technique [0002] The existing tunneling microscope has the following limitations in use. One is that the sample to be tested must be a conductive substance; the other is that the existing constant current mode tunneling microscope will be interfered by multiple external electron (current) sources. , the external field electron (flow) source includes incident electrons produced by the electron gun, secondary electrons, Oujie electrons, and photoelectrons excited by light; the third is that the bandwidth of the current-voltage converter is limited to tens of KHz. If the electron source is incident or leaves near a tunneling energy barrier, the external electron (electron) current and the tunneling current It will be amplified together by the current-voltage converter, thereby disturbing the existing current feedback m...

AI Technical Summary

Problems solved by technology

And by image 3 It can be seen that when the tunneling resistance Rt changes from 0.15M ohm to 0.4Mohm, the reflection coefficient changes from 45dB to 15dB, when the tunneling resistance Rt is 1M ohm, the reflection coefficient is 12dB, and when the tunneling resistance Rt is 10M ohm From 1G ohm to 1G ohm, because the change in reflection coefficient is too small, and they are almost indistinguishable at 11dB, so that it is practically difficult to distinguish the difference between the tunnel resistance 10Mohm and 100M ohm, and in practical applications, The tunnel resistance Rt usually operates in the range of 10M ohm to 1G ohm, so it is difficult to obtain useful signals by the above scanning method

[0006] In addition, by Figure 4 It can be seen that the radio frequency reflectivity intensity obtained by the above scanning method and the tunneling resistance Rt are not in a single correspondence relationship, that is to say, the same reflectivity intensity value will correspond to two values ​​of the tunneling resistance Rt, which will cause the scanning control circuit Misjudgment of the scanning result, and if the reflectivity feedback is used to control the height of the probe 10, an unstable situation will occur

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