On the Atomic-Force Microscopy and Electrical Properties of Single-Crystal Bismuth Films
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Atomic-Force Microscopy and Electrical Properties of Single-Crystal Bismuth Films V. M. Grabova, V. A. Geregaa, E. V. Demidova, *, V. A. Komarova, M. V. Starytsinb, A. V. Suslova, and M. V. Suslova aHerzen
State Pedagogical University of Russia, St. Petersburg, 191186 Russia National Research Center “Kurchatov Institute”–Prometey–Central Scientific Research Institute of Structural Materials, St. Petersburg, 191015 Russia *e-mail: [email protected]
b
Received December 21, 2019; revised January 25, 2020; accepted January 27, 2020
Abstract—A method for creating single-crystal bismuth films by melting and subsequent normal directed crystallization without a seed under a protective coating in a nitrogen atmosphere is proposed and tested. The high quality of the crystal structure of these films is confirmed by atomic-force microscopy and X-ray diffraction analysis. The specific resistance, magnetoresistance, and Hall coefficient are measured in the temperature range of 77–300 K. The electrical and galvanomagnetic coefficients of single-crystal bismuth films are compared with similar coefficients for block bismuth films created by thermal evaporation in vacuum. The mobilities of electrons and holes are determined in the temperature range 77–300 K for the studied structures. Keywords: bismuth, thin film, single-crystal film, atomic-force microscopy, transport phenomena DOI: 10.1134/S1027451020050055
INTRODUCTION The galvanomagnetic and thermoelectric properties of thin bismuth films are determined by the perfection of their structure: the number of defects, block sizes, and their crystallographic orientation [1–7]. Previous experiments on the preparation of films of bismuth and a bismuth–antimony solid solution by the method of floating-zone refining under a coating made it possible for the first time to solve the problem of obtaining single-crystal films of these compositions [8]. Positive results were obtained for films with a thickness of 200 nm to 3 μm on substrates of mica (muscovite) and polyimide using a protective coating of KBr. In the course of experiments on the floatingzone refining of films with a thickness of less than 200 nm, it was found that such films are compressed into droplets during floating-zone melting under a coating. Also, the method has a restriction on the material and the thickness of the substrates. It is required that the substrates have a sufficiently low thermal conductivity, otherwise, difficulties arise in obtaining a stable melt zone of small width. In this work, we test a method for producing singlecrystal bismuth films by melting and subsequent normal directed crystallization without a seed under a protective coating in a nitrogen atmosphere. Using atomic-force microscopy and X-ray diffraction analysis, the structure of the films is studied. The galvano-
magnetic coefficients of these films are compared with similar coefficients for bismuth films obtained by thermal evaporation in vacuum. The study shows the high perfection of bismuth films obtained by the proposed method. EXPER
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