TECHNICAL FIELD

The present invention relates to a method for analyzing movement characteristics of charges or holes of a nano-electronic material, and more particularly, to a method for analyzing vertical movement characteristics of charges of a thin film material by omitting a part of a metal electrode and irradiating the surface of a sample with a particle beam including electrons, light, and the like.

BACKGROUND ART

Many studies and investments have been made by companies and organizations with regard to electronic materials used in electronic products that are essential for the daily life of modern people.

A significant portion of the important functions of electronic materials is related to the flow of charges, but until now, the main focus has been on understanding the planar moving line of current in the electronic materials.

However, with resistance switching devices with a sandwich structure and three-dimensional (3D) integration of the electronic materials receiving attention, characteristic information on charge movement in a vertical direction is a key concern for overcoming technical limitations in related fields and improving competitiveness.

In particular, as the thickness of a material becomes smaller in nanometer units, physical properties are more likely to be distorted due to the formation of metal electrodes, and thus vertical movement characteristics of electrons or holes of a nano-thin film are important in order to rapidly transfer electronic information of application materials.

In the case of 3D phase insulator samples that are being actively studied recently, when the samples are measured by a conventional electrode patterning method, there is a risk of breaking the physical properties of the samples due to the interaction between an electrode and the sample, and thus there is a need for a method for electrodeless measurement of the physical properties of the sample.

In addition, in the case of a resistive random-access memory (ReRAM) device that is spotlighted as a next-generation memory that may replace a conventional flash memory, there are many challenges that should be overcome for commercialization, and in order to solve these problems, it is essential to understand the change mechanism in vertical movement characteristics of charges of the material without a metal electrode.

Accordingly, the present invention overcomes this and applies the overcoming to a development stage of a material to analyze the vertical movement characteristics of a device and thus provides a method that may be utilized to understand real-time feedback of material properties and charge movement mechanics of the material.

DISCLOSURE

Technical Problem

The present invention has been made in view of the above-mentioned problems and is directed to providing a method for measuring the vertical movement characteristics of charges of a nanometer-sized ultra-thin sample, in which the effect of an electrode is eliminated.

The present invention is also directed to providing a method for analyzing vertical movement characteristics of charges of a thin film stacked structure.

Objectives of the present invention are not limited to the objectives described above, and the other objectives which are not described above will be clearly understood by those skilled in the art from the following specification.

Technical Solution

One aspect of the present invention provides a method for measuring electron mobility, which is performed by an apparatus including a chamber forming a sealed space, an electron gun provided in the chamber, and a metal sample provided in the sealed space to face the electron gun, the method including an electron irradiation step of irradiating the metal sample with electrons using the electron gun, a sample current measurement step of applying a voltage to the metal sample to measure a sample current according to the applied voltage on the metal sample, a secondary electron current calculation step of calculating a secondary electron current through the measured sample current, and an effective incident current definition step of defining the sum of the measured sample current and the calculated secondary electron current as an effective incident current.

The method may further include an electron mobility measurement step of measuring electron mobility in the metal sample using a value of the defined effective incident current and Equation 4,
JEP(μ)=−1/(1−δEP)×μKBT∇q/eEquation 4

where JEPis the effective incident current, μ is charge mobility, δEPis the number of secondary electrons generated by one electron per unit time, KBis a Boltzmann constant, T is an absolute temperature, ∇q is a value obtained by differentiating charge distribution in the sample, and e is a charge amount of the electron.

The secondary electron current calculation step may include obtaining data for secondary electron distribution according to kinetic energy by differentiating values of the measured sample current, calculating a schematic curve for distribution of the obtained data and selecting an equation from which a curve having a form similar to that of the calculated curve is derived, fitting a graph according to the derived equation into a curve for the distribution of the data, and obtaining secondary electron current data by integrating the fitted curve with the voltage.

Another aspect of the present invention provides a method for measuring hole mobility, which is performed by an apparatus including a chamber forming a sealed space, a photon supply unit provided in the chamber, and a metal sample provided in the sealed space to face the photon supply unit, the method including an electron irradiation step of irradiating the metal sample with photons through the photon supply unit, a sample current measurement step of applying a voltage to the metal sample to measure a sample current according to the applied voltage on the metal sample, a secondary electron current calculation step of calculating a secondary electron current through the measured sample current, and an effective incident current definition step of defining the sum of the measured sample current and the calculated secondary electron current as an effective incident current.

The method may further include a hole mobility measurement step of measuring hole mobility in the metal sample using a value of the defined effective incident current,
JEP(μ)=−1/(1−δEP)×μkBT∇q/eEquation 4

where JEPis the effective incident current, μ is charge mobility, δEPis the number of secondary electrons generated by one electron per unit time, KBis a Boltzmann constant, T is an absolute temperature, ∇q is a value obtained by differentiating charge distribution in the sample, and e is a charge amount of the electron.

The secondary electron current calculation step may include obtaining data for secondary electron distribution according to kinetic energy by differentiating values of the measured sample current, calculating a schematic curve for distribution of the obtained data and selecting an equation from which a curve having a form similar to that of the calculated curve is derived, fitting a graph according to the derived equation into a curve for the distribution of the data, and obtaining secondary electron current data by integrating the fitted curve with the voltage.

Still another aspect of the present invention provides an electron mobility measuring apparatus including a chamber forming a sealed space, an electron gun provided in the chamber and configured to irradiate the sealed space with an electron beam, a metal sample provided in the sealed space to face the electron gun, a voltage supply configured to apply a voltage to the metal sample, and a current measuring device configured to measure a current according to the voltage applied through the voltage supply.

The metal sample may include an active layer and an electrode located on a rear surface of the active layer, and the voltage supply and the current measuring device may be electrically connected to the electrode.

Yet another aspect of the present invention provides a hole mobility measuring apparatus including a chamber forming a sealed space, a photon supply unit provided in the chamber and configured to irradiate the sealed space with photons, a metal sample provided in the sealed space to face the photon supply unit, a voltage supply configured to apply a voltage to the metal sample, and a current measuring device configured to measure a current according to the voltage applied through the voltage supply.

The metal sample may include an active layer and an electrode located on a rear surface of the active layer, and the voltage supply and the current measuring device may be electrically connected to the electrode.

Advantageous Effects

An electrodeless analysis method of vertical movement characteristics of charges of a nano-electronic material of the present invention has the following effects.

First, an expensive electrode patterning process for analyzing movement characteristics of electrons or holes is not required, which can contribute to a reduction in material development cost and time.

Second, vertical movement characteristics of electrons or holes of a material can be simply analyzed just by adding a voltage application unit or a current measurement unit to an apparatus including a light source or an electron source.

Third, material properties can be grasped in real time by simultaneously measuring the electrical and chemical properties of a material, thereby providing information on the design of an electronic structure and on the development of customized materials using the same.

It should be noted that advantageous effects of the present invention are not limited to the above-described effects, and other effects that are not described herein will be apparent to those skilled in the art from the following descriptions.

