The √7×√3 surface reconstruction consisting of a triple indium layer on the Si(111) surface

抄録

Atomically thin indium layers grown on the Si(111) substrate have attracted much interest and have been extensively studied, since the two-dimensional (2D) superconductivity was reported to appear below about 3 K on the so-called ‘rect’ structure of the Si(111)-√7×√3-In surface (referred to as √7×√3-rect). In our previous studies, the adsorption of organic molecules on the √7×√3-rect reconstruction was investigated [1-2].

In the present study, the formation process of the √7×√3-rect is studied in detail by varying the post-heating temperature after indium deposition on the Si(111) substrate, using the STM and the LEED. We find that at a low post-heating temperature of about 400 ºC, 2D indium islands of tens of nm in size are formed, consisting of a triple indium layer with a √7×√3 reconstruction different from the √7×√3-rect reconstruction (referred to as √7×√3-TL), as shown in Fig. 1(a) and 1(b). Although the atomic arrangements in the topmost indium layers of the √7×√3-TL and the √7×√3-rect reconstructions are considered to be nearly the same, their dIt/dVs(Vs) curves look different from each other. Surface defects in the disordered region around the √7×√3-TL islands seen in Fig. 1(a) originate from the partially remaining 7×7 reconstruction at the interface between the Si substrate and the indium layers. Additional indium atoms evaporated on the √7×√3-rect surface with the √7×√3-TL islands form flat wide single indium layers incorporating the √7×√3-TL islands. However, the layers do not adopt the √7×√3-TL reconstruction, but the incommensurate ~5.4×~5.4 reconstruction [3].

References

[1] T. Suzuki, et.al., Nanoscale 11 21790 (2019).

[2] T. Suzuki, et.al., Phys. Chem. Chem. Phys. 22 14748 (2020).

[3] T. Suzuki, et. al., Surf. Sci. 726 122174 (2022).