Method for measuring surface charge density of materials

Abstract

The invention provides a method for measuring the surface charge density of materials based on a conductive point of a scanning probe microscope, which comprises: a) scanning the surface appearance of a sample to be measured; b) measuring the change of a phase angle difference delta theta between actuating and alternating signals for driving the point to oscillate and actual oscillator signals of the point and a corresponding point bias Vt; c) according to a relation of the delta theta and the Vt, fitting the delta theta and the Vt obtained in step b) to obtain an index; and d) according to the index obtained in step c), searching the surface charge density corresponding to the index in a calibration curve based on the relation of the delta theta and the Vt, wherein the calibration curve is a relation curve of the surface charge density delta s of a standard sample and a coefficient a1. The method overcomes the difficulty of establishing a simple model for a geometrical shape of the point in the prior art, does not need considering the concrete geometrical shape of the point, makes the measurement simple and the operation easy, and has important significance for researching functions of nanodevices and nanostructures.

Description

technical field [0001] The invention belongs to the technical field of surface analysis, and in particular relates to a method for measuring surface charge density of a material with a conductive tip of a scanning probe microscope (SPM for short). Background technique [0002] In the current market, the long-range electrostatic interaction force between the tip and the sample can be measured by acting on the bias voltage of the conductive tip or the sample, which can be used to detect the surface potential of the sample, the static and dynamic properties of ferroelectric materials, single nanometer The electrical transport characteristics of the tube and so on. The tip of a general Conductive Scanning Probe Microscope (CSPM) is an irregular pyramid-shaped tip. The electric field intensity generated by the charged charge on the tip has a lot to do with the shape of the tip and the distance between the tip and the sample. For a specific The electric field strength generated b...

AI Technical Summary

Problems solved by technology

This type of method takes the geometric structure of the needle tip into consideration. Due to the uncertainty and complexity of the geometric shape of the needle tip, it is more complicated to quantitatively detect the charge density on the surface of the sample in the nanometer scale based on CSPM, and different types of needle tips require different methods. The needlepoint model of

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