Since the energy spectrum of bismuth charge carriers is highly sensitive to mechanical deformations, studying their influence, leading to an increase or decrease in the overlap of actual extrema, on the transport properties of charge carriers in ultrathin bismuth films makes it possible to investigate the combination of manifestations of the quantum size effect and metallic surface states. In this work, the temperature dependencies of the electrical and galvanomagnetic properties of thin bismuth films (10-1250 nm) are studied under conditions of in-plane tensile and compressive deformation. Deformations are created as a result of the difference in the coefficients of thermal expansion of the film and substrate materials. Silicon with an oxidized surface, mica, and polished cleavage (111) CaF2 F 2 are used in order to create either tensile and compressive deformations. The presence of film deformations is confirmed by XRD. The magnitude of deformation is calculated based on the CTEs of the materials. The absence of mechanical stress relaxation or the formation of additional defects during temperature measurements is confirmed by the absence of hysteresis of properties in the range of 77-300 K. Based on the experimental results, the mobilities and concentration of charge carriers are calculated within the framework of the two-band model. As the film thickness decreases to less than 100 nm, an increase in the charge carrier concentration is observed, which is associated with metallic surface states. It is shown that the magnitude of the effect of deformation on the concentration of charge carriers in films of all thicknesses remains unchanged.

Due to the sensitivity of the electronic structure of semi‐metals to small distortions of the crystal lattice, the study of the electrical and galvanomagnetic properties of bismuth films requires taking into account the deformation that occurs in the film‐substrate system due to the difference in the thermal expansion of the film and substrate materials. The magnitude of these deformations plays an important role in analyzing the temperature dependencies of the transport properties of charge carriers. The paper presents an experimental study of the magnitude of deformation of bismuth films on various substrates at 300 and 77 K using X‐ray diffraction. Changes in the lattice constant of crystallites, the trigonal axis of which is perpendicular to the film plane, depending on the substrate material, are obtained. A comparison between the assessment of the deformation of these crystallites in the film plane based on Hooke's law and the difference in the coefficients thermal expansion of the film and substrate materials is made.

The paper is devoted to the study of transverse electric field effect on transport properties of charge carriers in bismuth and bismuth-antimony thin films. Experimental results reveal the existence of electric field effect in thin films of composition up to 12 at.% Sb. The dependencies of resistance on magnitude of electric field are obtained in a wide range of film thicknesses. A qualitative interpretation of the observed effect is given based on the analysis of the mobility of electrons and holes in films depending on the sign of the electric field and the film thickness.

The paper presents the results of a study of the electrical, galvanomagnetic, and thermoelectric properties of Bi and Bi1-xSbx (x = 0.03, 0.05, and 0.12) thin films (10-50 nm) on a mica substrate. All samples are characterized by an increase in conductivity with a de-crease in film thickness, which can be associated with the presence of topologically protected surface states. It has been found that the band structure of the alloys significantly affects the appearance of the metallic type of conductivity in films with a < 18 nm thickness. It was found that the resistivity of Bi0.97Sb0.03 films < 17 nm thick is almost independent of temperature. Despite the increase in the conductivity of the samples, with a decrease in the thickness, the thermoelectric power factor decreases, which casts doubt on the fact that surface states have a positive effect on the thermoelectric figure of merit of thin Bi1-xSbx films. However, the detection of a positive thermoelectric power in Bi0.88Sb0.12 samples may be of interest in the development of the p branch of thermoelectric converters.

Due to the small indirect overlap of the valence and conduction bands, as well as the small direct band gap sensitive to external impact, bismuth is of great interest for stress engineering of band structure. In this work, we study the effect of uniaxial deformation along the trigonal axis of a bismuth crystal on its band structure using the density functional theory modeling. A transition to the semiconductor state occurs upon compressive deformation along the trigonal axis, as well as a transition to the gapless state at the L-point upon tensile deformation. The obtained results provide a deeper understanding of the patterns of change in the band structure of bismuth under uniaxial deformation and will serve as a basis for the analysis of the experimental results of studying the transport properties of thin bismuth films under conditions of in-plane deformation.

2D materials with van der Waals (vdW) gaps between covalently bonded blocks are in the focus of modern semiconductor science and technology. Of special interest is the possibility to control their properties through the vdW gap reconfiguration. Herein, using first‐principles simulations it is demonstrated that uniaxial compression of GaSe, counterintuitively, does not serve to close the gap but, instead, changes the dimensionality from 2D to quasi‐1D, with flat GaSe chains oriented along the applied pressure. The structural change is accompanied by drastic changes in electronic structure. The inability to close the vdW gap to the antibonding nature of Se–Se interactions is attributed.

The results of a study of the semimetal films deformation produced by dome bending of the substrate are presented. Deformation control was carried out by means of X-ray diffraction analysis. It is shown that the dome bending method can be used to study films under planar deformation in a film-substrate system with different thermal expansion coefficients. The maximum in-plane deformation for bismuth films of 1 mkm thickness order was found. It was shown that the deformation created by the dome bending of the substrate in combination with the use of substrates with different temperature expansion makes it possible to obtain a relative in-plane deformation of bismuth films up to 0.8% at 300 K.

This paper presents the results of studying the magnitude of the strain of semimetal films created by the dome bending of the substrate. The deformation is controlled by X-ray diffraction (XRD) analysis. It is shown that the dome bending method can be used to study films under conditions of the in-plane deformation that occurs in the film-substrate system due to the difference in the coefficients of thermal expansion of the film and substrate material. It is established that the deformation created by the dome bending of the substrate in combination with the use of substrates with a different thermal expansion makes it possible to obtain a relative in-plane deformation of bismuth films up to 0.8% at 300 K.

The reasons for increasing the charge carriers concentration in thin bismuth films are discussed. The concentration was calculated on the basis of the measured electrical and galvanomagnetic coefficients at the temperature 77K under the two-band approximation and the assumption that the charge carriers free path in the film is isotropic.

The reasons for increasing the charge carriers concentration in thin bismuth films are discussed. The concentration was calculated on the basis of the measured electrical and galvanomagnetic coefficients at the temperature 77 K under the two-band approximation and the assumption that the charge carriers free path in the plane of the film is isotropic. Keywords: Bismuth, thin film, charge carriers concentration, surface.

The study of the electronic properties of ultrathin films of pure bismuth and bismuth-antimony alloys is of interest, since an increase in conductivity with decreasing sample thickness was found. This paper presents the results of an experimental study of the structure, electrical, galvanomagnetic and thermoelectric properties of pure bismuth and Bi1-xSbx thin films (x=0.05 and 0.12) on a mica substrate in the thickness range of 10-30 nm. An increase in the conductivity with a decrease in the thickness of the samples was found. It may be due to the presence of topologically protected surface states. It is shown that the features of the manifestation of this effect are significantly influenced by the alloys band structure. The form of the temperature dependences of the Seebeck coefficient casts doubt on the fact that surface states have a positive effect on the thermoelectric efficiency of thin bismuth-antimony films. However, the detection of a positive thermoelectric power in Bi0.88Sb0.12 samples can become an important factor for searching for the possibility of creating a p-branch of thermoelectric converters. Keywords: bismuth, antimony, thin films, surface states, thermoelectric power.

The study of the electronic properties of ultrathin films of pure bismuth and bismuth-antimony alloys is of interest, since an increase in conductivity with decreasing sample thickness was found. This paper presents the results of an experimental study of the structure, electrical, galvanomagnetic and thermoelectric properties of pure bismuth and Bi1−x Sbx thin films (x = 0.05 and 0.12) on a mica substrate in the thickness range of 10−30 nm. An increase in the conductivity with a decrease in the thickness of the samples was found. It may be due to the presence of topologically protected surface states. It is shown that the features of the manifestation of this effect are significantly influenced by the alloys band structure. The form of the temperature dependences of the Seebeck coefficient casts doubt on the fact that surface states have a positive effect on the thermoelectric efficiency of thin bismuth-antimony films. However, the detection of a positive thermoelectric power in Bi0.88Sb0.12 samples can become an important factor for searching for the possibility of creating a p-branch of thermoelectric converters.

The paper presents the results of measuring the thermopower and resistivity of bismuth films in the thickness range from 1 μm to 10 nm, obtained by thermal evaporation in vacuum. The study is carried out in the temperature range 77–300 K by a method excluding the introduction of additional deformation into the film-substrate system by elements of the measuring cell. Plates of single-crystal mica (muscovite) are used as substrates. A significant dependence of the thermopower and thermoelectric power on the film thickness is found. The results are interpreted within the framework of classical and quantum-size effects of the restriction of the thickness and size of crystallites.

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.

We report on the production of 200 and 600 nm thick Bi films on mica substrate with 10 nm thick Sb sublayer between Bi and mica. Two types of films have been studied: block and single crystal. Films were obtained using the thermal evaporation technique using continuous and discrete spraying. Discrete spraying allows smaller film blocks size: 2–6 μ m compared to 10–30 μ m, obtained by the continuous spraying. Single crystal films were made by the zone recrystallization method. Microscopic examination of Bi films with and without Sb sublayer did not reveal an essential distinction in crystal structure. A galvanomagnetic study shows that Sb sublayer results in the change of Bi films properties. Sb sublayer results in the increase of specific resistivity of block films and has no significant impact on single crystal films. For single-crystal films with Sb sublayer with a thickness of 200 nm the Hall coefficient has value 1.5 times higher than for the 600 nm thickness films at 77 K. The change of the Hall coefficient points to change of the contribution of carriers in the conductivity. This fact indicates a change in the energy band structure of the thin Bi film. The most significant impact of the Sb sublayer is on the magnetoresistance of single-crystal films at low temperatures. The increase of magnetoresistance points to the increase of mobility of the charge carriers. In case of detecting and sensing applications the increased carriers mobility can result in a faster device response time.

In recent theoretical works devoted to topological insulators, it was shown that, in addition to the state of a topological insulator, due to the presence of the inverse initial state and the presence of symmetry with respect to time inversion with the topological invariant Z2, in the electronic energy spectrum of charge carriers of crystals like bismuth, states of a topological insulator can be realized due to the specific boundary conditions, as well as the presence of rotational symmetry, with a higher order topological invariant. During this work, we wanted to detect the signs of the topological insulator state in the galvanomagnetic properties of thin bismuth films, which have a significant difference in the quality of the crystal structure.