Nickel antimonide belongs to the class of binary pnictides, the crystal lattice of which is formed by a compound of a transition metal, in this case nickel, with a pnictogen, in this case antimony, and belongs to the space group P63/mmc with hexagonal lattice parameters a = 3.953 Å and c = 5.141 Å. It is found quite rarely in nature in the form of the mineral breithauptite. Studies of polycrystals of nickel antimonide have shown the presence of Pauli paramagnetism in them [1]. The combination of magnetic and structural properties of NiSb makes this material very promising for spintronics applications. To date, a very limited number of studies have been published on the growth of NiSb films. Thus, in [2], single-crystal films of nickel antimonide were deposited on a gallium arsenide substrate using molecular beam epitaxy. The production of polycrystalline NiSb films by magnetron sputtering of a target pressed from a mixture of nickel and antimony was reported in [3].

This paper presents the results of a study of the growth and structural characteristics of thin films of nickel antimonide, first obtained by deposition of a thin layer of nickel on a heated gallium antimonide substrate.

To deposit nickel films, magnetron sputtering of a nickel target at direct current in an argon atmosphere was used. The residual pressure in the chamber was 10–6 mbar. The substrate was heated to a given temperature, which in different experiments varied from room temperature to 300°C. Then, argon was filled into the chamber to a pressure of 6 × 10–3 mbar. The film deposition rate was maintained at 400 nm/h. After deposition, the structure of the films was studied by X-ray diffractometry using a DRON-3 automated double-crystal diffractometer with a quartz monochromator. The X-ray tube radiation wavelength was 0.15406 nm.

The deposition of a nickel film on an unheated substrate, as expected, led to the growth of an amorphous nickel layer, as evidenced by the diffraction pattern shown in Fig. 1a. When the film was deposited onto a substrate heated to 300°C, the formation of a nickel antimonide film was observed. In the diffraction pattern (Fig. 1b), in addition to the peaks from the GaSb substrate, one can see a single peak corresponding to reflection from plane (10\(\bar {1}\)1) of nickel antimonide. To determine the degree of film misorientation, the rocking curve shown in Fig. 2 was measured. The half-width of the rocking curve was approximately 1.5°, which indicates that the resulting film was quite well oriented. When shooting a sample rotating around an axis perpendicular to the plane of the substrate (the so-called phi-scan), no preferred orientation was detected. This means that in this case there is an axial texture (101). Typically, materials with a hexagonal crystal lattice are characterized by the formation of an axial texture along the [001] direction due to the fact that the (001) plane has the lowest surface energy, and under equilibrium conditions, this growth direction is the most energetically favorable. Under the conditions described in this article, an unusual orientation of the texture axis is observed. This can be explained by the fact that in this case the crystallization process is not equilibrium. The formation of texture precisely along the [101] axis is due to the fact that in the structure of indium antimonide the (101) plane is a cleavage plane, which is characterized by the lowest adhesion force between planes with these indices. To determine the effect of subsequent annealing on a nickel film deposited at room temperature, the resulting structure, immediately after deposition, was placed in a vacuum oven at a temperature of 300°C for 1 h. It turned out that in this case the formation of nickel antimonide also occurs, but there is no texture. The diffraction pattern shown in Fig. 3 shows the presence of a NiSb polycrystal without a preferred orientation. Using the Scherrer method, the sizes of coherent scattering regions were determined from the width of diffraction lines. They amounted to 15 nm with a film thickness of about 40 nm.

Fig. 1.
figure 1

X-ray diffraction patterns of films deposited on a gallium antimonide substrate: (a) after deposition of nickel onto an unheated substrate; (b) after nickel deposition at a temperature of 300°C.

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Fig. 2.
figure 2

Rocking curve from the (101) plane of the nickel antimonide film.

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Fig. 3.
figure 3

X-ray diffraction pattern after annealing of a nickel film deposited on an unheated substrate.

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Thus, as a result of the conducted studies, it was shown that when a thin nickel film is deposited on a gallium antimonide substrate, a nickel antimonide layer is formed in the form of an axial texture with (101) orientation, perpendicular to the substrate surface.