SU1763997A1 - Contact potential difference metering method - Google Patents

Abstract

Usage: the invention relates to the measurement technique and can be used to control the purity, degree of activation and energy state of the surface layers according to the magnitude of the electron work function. Summary of the Invention: In order to increase the accuracy and reproducibility of the results and expand the scope of application, the measuring electrode 3, made in the form of a grid, is completely shielded, using the test sample 4 as one of the walls of the screen 1. The electron flow directed through the gap between the measuring electrode and the sample in the ionization chamber 2 as a result of a self-glowing discharge between the discharge electrode 11 and the walls of chamber 2. A negative potential is applied to the body of the ionization chamber, It provides for deposition on the inner side of the chamber of positive ions and electron beam focusing. The stabilization of the medium in the gap to obtain a constant value of the contact potential difference is carried out by moving the measuring electrode relative to the sample under study, moving the chamber 2 relative to the measuring electrode. The resulting value is considered to be actual, and the discharge current, measured by the discharge current meter 10, is calibration. When the measurement conditions change, the discharge current is calibrated by changing the output voltage of the high-voltage unit 8 using a potentiometer 9. A device for implementing the method also contains a DC amplifier 5, a measuring device 6 and a protective circuit 7. 1 Cp f-ly, 1 ill.

Description

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The invention relates to a measurement technique and can be used to control the purity, degree of activation, and energy state of the surface layers in terms of the electron work function.

The aim of the invention is to improve the measurement accuracy and expand the field of application by measuring the contact potential difference of samples with dielectric films.

The goal is achieved by increasing the electrical conductivity of the medium in the gap of the measuring electrode — the sample under study is not carried out by ionizing the medium in the gap itself, but by using a stream of electrons directed into the gap normal to the surface of the sample from the ionization chamber, the open end of which faces the gap from the side of the measuring electrode, made in the form of a grid, and in which they create a self-glowing discharge, and a negative potential is applied to the chamber walls, thereby focusing the flow of electrons and the neutral the study appearing in the glow discharge ion. By changing the gap between the measuring electrode and the sample under study, the measuring electrode and the open end of the ionization chamber, stable values of the contact potential difference are achieved. At the same time, the current flowing in the discharge circuit and characterizing the number of charge carriers formed, directed into the gap between the IE and the test sample, is measured. The current value at which stable readings of the PKK values are obtained is considered to be a calibration. When performing subsequent measurements under conditions different from the tuning conditions, the instrument is calibrated by adjusting the discharge current.

The drawing shows a device for carrying out the proposed method.

The device contains a screen 1, a metal ionization chamber 2, on the walls of which positive ions are precipitated, which are formed during the glow discharge in chamber 2, and a focused electron flow is directed into the gap between the measuring electrode 3 and the test sample 4, the DC amplifier 5, a measuring device 6, a conductive protective circuit 7, a high-voltage unit 8 with a regulating potentiometer 9, a discharge current meter 10 and a discharge electrode 11 Placed inside the screen 1 is an ionization chamber 2 and measuring electrode 3 is formed in

grid view, mounted coaxially with the possibility of axial movement relative to each other.

Screen 1 is made with an open end

on the side of the measuring electrode, by which it is installed on the sample under study A. The measuring electrode 3 is electrically connected to the input of a DC amplifier 5, the output of which

connected to the input of the measuring device 6. Along the perimeter there is a protective conductive circuit 7, electrically isolated from the measuring electrode 3. Circuit 7 is connected to the output of the DC amplifier 5. Screen 1, the metal ionization chamber 2 is connected to the common case of the device. The ionization chamber 2 and the measuring electrode 3 are installed in the screen 1, for example, by means of threaded connections, which allow axial movement of the ionization chamber 2 and the measuring electrode 3 in the screen 1.

The discharge electrode 11, which is a bare conductor, is rigidly fixed with a dielectric sleeve in the housing of the ionization chamber 2, and is connected through the discharge current meter 10 to the high-voltage unit 8, the output

the voltage of which is regulated by potentiometer 9,

The method is implemented as follows.

Using a potentiometer increase

the output voltage of the high-voltage unit 8 to the occurrence of a glow discharge detected by the discharge current meter 10.

The screen of the device with an open end face is installed on the sample surface. Change the conductivity of the medium in the gap between the measuring electrode 3 and the test sample 4, the movement of the measuring electrode 3 relative to

details or by moving the ionization chamber 2 relative to the measuring electrode 3 with a constant gap between the measuring electrode 3 and the sample 4, achieve the value of the contact difference

potentials equal to zero. This value is considered true because Samples and measuring electrode are made of one alloy. The value of the discharge current at which the results were obtained is plotted on

The scale of the current meter is low, and is considered to be kapirovochny. The samples are then placed in a climate chamber and measured at different values of humidity and temperature.

Using the proposed method of measuring the magnitude of the contact potential difference allows to increase the accuracy and reproducibility of the results when environmental conditions change, to obtain stable values when thin dielectric films are present on the surface. The method and device for its implementation are environmentally friendly and do not require special precautionary measures.

Claims (2)

Claim 1. The method of measuring the contact potential difference, in which the measuring electrode is completely shielded as a grid, increases the electrical conductivity of the medium in the gap between the measuring electrode and the sample under study, measures the potential difference between them and makes Beating the medium in the gap by moving the measuring elec- trop relative to the sample being monitored and the radiation source relative to the measuring electrode in the direction normal to their surface until a constant potential difference is obtained, which is such that, in order to increase the measurement accuracy and expand the scope, increase electrical conductivity the medium in the gap between the measuring electrode and the test sample is carried out using an electron beam directed along the normal to the surface of the sample from the ionization chamber in which create singly glow discharge, while a negative potential is fed to the wall. 2. The method according to claim 1, wherein that the calibration is carried out by the magnitude of the discharge current,