RU2452934C2 - Method of preparing thin bismuth films on mica for detecting boundaries of units via atomic force microscopy - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method involves preliminary decoration of a surface by oxidation. Preliminary processing of the surface is carried out by decorating and the decorating agent used is oxygen.

EFFECT: enabling detection of intercrystalline boundaries and determining the size of crystals of submicron films.

2 dwg

Description

Usage: in condensed matter physics, materials science to determine the size of blocks.

The essence of the invention lies in the fact that to identify the intergranular boundaries of thin bismuth films on mica substrates by atomic force microscopy (AFM), the surface of the sample is pre-decorated using oxidation. Oxygen is used as a decorating agent. Decorating oxidation is carried out under atmospheric conditions in an atmosphere of air or another gas mixture containing oxygen in an amount of about 20% at a temperature of 5-50 ° C.

EFFECT: using the proposed method, the intergranular boundaries are detected and the crystallite sizes of submicron films are determined in contrast to existing analogues.

The invention relates to materials science, and in particular to methods for studying the structure.

Known methods for detecting the intergranular boundaries of bismuth films on mica, based on preliminary preparation of the sample using selective chemical etching [1] and the subsequent study of the surface topography under a microscope. Another way to determine crystallite sizes is to analyze line broadening in X-ray diffraction patterns [2]. The disadvantage of this method is its indirect nature and the possibility of systematic errors associated with the influence of a number of other factors (microstresses in the sample, instrumental broadening, etc.)

The closest known method is the use of selective chemical etching. As an etchant for bismuth, a dilute aqueous solution of a mixture of acetic acids (6 parts) and nitric (7 parts) is used. Etching is carried out for 2-20 seconds [1].

The disadvantage of this method is its destructive nature, the complexity of the etching mode selection and the difficulty of using submicron thicknesses for films.

The purpose of the invention: the detection in the films of bismuth on the mica of the boundaries of the blocks by the AFM method to determine their size.

The goal is achieved by preliminary preparation of the sample by decorating the boundaries of the blocks using oxidation.

Technological parameters of the oxidation process: oxidation is performed under atmospheric conditions in an atmosphere of air or other gas mixture containing oxygen in an amount of about 20% at a temperature of 5-50 ° C.

The minimum time required for decoration linearly depends on the film thickness and is about 1 day at 8 nm thickness. The long-term presence of a bismuth film in a decorating medium leads to a more uniform oxide coating of the surface of the bismuth film, which complicates the detection of crystallite boundaries by the AFM method.

To identify the intergranular boundaries after oxidation, the study of the surface structure of the film should be carried out by atomic force microscopy using an atomic force or scanning probe microscope, with a sensitivity of no worse than 0.5 nm in height and a resolution of no worse than 50 nm in the XY plane. After the oxidation, the surface of the bismuth film acquires an additional texture in the form of closed lines of irregular shape several nanometers high and about 50 nm wide (figure 1), in contrast to the surface of the originally taken film before oxidation (figure 2), which is reflected in the AFM images of these surfaces.

The proposed method for the preparation of samples can be used for other materials with appropriate selection of the atmosphere and decoration mode.

List of figures

Figure 1: The figure shows an AFM image of the surface of a bismuth film on a mica subjected to oxidation dressing. Arrows show examples of decorated crystallite boundaries.

Figure 2: The figure shows an AFM image of the surface of the bismuth film on mica, not subjected to oxidation.

Literature

1. Mikhaylichenko T.V. Production Conditions and Electrical Properties of Bismuth Films: Dis .... Cand. - math. Leningrad, 1973, 135 p.

2. Sharenkova N.V. The influence of structural features on the physical properties of rare-earth semiconductors based on samarium sulfide: Abstract of thesis ... cand. Phys.-Math. sciences. St. Petersburg, 2009, 16 p.

Claims (1)

A method of preparing thin bismuth films on mica-muscovite to detect intergranular boundaries by atomic force microscopy, including preliminary surface decoration using oxidation, characterized in that the surface preliminary treatment is carried out by decoration, using oxygen as a decoration agent.

Images