The Dynamical Observation of α-Sn (111) This Films Grown on InSb (1̄1̄1̄) by RHEED

Abstract

The α-Sn (111) films of 150 monolayers (ML) will grow at room temperature on thermally cleaned InSb (1̄1̄1̄) substrates having a 2×2 reconstructed surface. The α-Sn (111) surfaces are observed to most clearly exhibit a 3×3 reconstruction at a film thickness of 30 ML by reflection high energy electron diffraction (RHEED). When the 30 ML films are heated at 170°C, the liquid phase begins to appear without the transition to the β-phase. From these result, effects of the InSb (1̄1̄1̄) substrate on the thermal stability of the α-Sn (111) film are discussed.

Characterization of Au thin films deposited on α-Sn(111)-(3×3)/InSb(111)A surfaces

“…It was confirmed by RHEED observations performed along ½2 1 1 and ½0 1 1 azimuths of the thermally cleaned InSb(1 1 1)A substrate prepared by a MBE method that the thermally cleaned InSb(1 1 1)A surface (lattice constant: a ¼ 0:64798 nm) has a 2 Â 2 reconstructed structure [3,5,[9][10][11]. Figs.…”

“…An analysis of fundamental reflections marked by large arrows and reflections marked by small arrows in Fig. 1 indicates that the a-Sn(1 1 1) surface (lattice constant: a ¼ 0:6489 nm) grown on InSb(1 1 1)A-(2 Â 2) at 50 1C has a 3 Â 3 reconstructed structure [3,5]. The results of RHEED observations of a-Sn(1 1 1) surface grown on InSb(1 1 1)A-(2 Â 2) substrates at RT were similar to those of a-Sn(1 1 1) surface grown at 50 1C, although the diffraction pattern of the latter was sharper than that of the former, which meant that the crystallinity of a-Sn(1 1 1) surface grown at 50 1C was better than that grown at RT.…”

“…The first cleaning treatment of the substrate surface in the MBE system was performed by heating for 20 min at 460 1C with Sb 4 beams [3,5,8], which were evaporated from an effusion cell of Ta, impinging onto the substrate at a rate of 3.8 Â 10 16 (atoms/(m 2 s)). The second treatment was as follows: Molecular beams of In 1 and Sb 4 were impinged on InSb(1 1 1)A substrates at 330 1C with fluxes of In 1 (4.8 Â 10 16 (atoms/(m 2 s))) and Sb 4 (5.5 Â 10 16 (atoms/ (m 2 s))).…”

“…In order to examine the interface between the Au thin film and the a-Sn/InSb semiconductor superlattice, atomically flat and clean surfaces of a-Sn thin films with a well-defined surface structure have to be prepared on InSb substrates that have a wider band gap than a-Sn. Although the bulk Sn is known to have a semiconducting a-phase with a diamond structure and an identically zero gap at temperature below 13.2 1C, and to have a metallic b-phase with a tetragonal structure above this temperature, Sn films grown on InSb substrates are reported to have an a-phase even above room temperature (RT) [2][3][4][5][6][7]. The (1 1 1) surface of the a-Sn film grown on an InSb(1 1 1)A-(2 Â 2) was reported to show different surface reconstructions depending on the cleaning methods of the substrate [5].…”

“…The (1 1 1) surface of the a-Sn film grown on an InSb(1 1 1)A-(2 Â 2) was reported to show different surface reconstructions depending on the cleaning methods of the substrate [5]. That is, 3 Â 3 and 2 Â 2 reconstructions of the a-Sn(1 1 1) surface were observed on the cleaned InSb(1 1 1)A surface prepared by using the molecular beam epitaxy (MBE) method [3,5], while only a 1 Â 1 reconstruction was observed in the case of cleaning by repeated sputtering and annealing [2,4,6,7]. It was reported that this difference cannot result from the diffusion of In atoms into the Sn overlayer, and that, taking into account that the 3 Â 3 and 2 Â 2 reconstructions observed at lower temperature transformed into a 1 Â 1 structure at higher temperatures [5], one possible explanation is the disordering of the surface Sn atoms, which can be produced by the presence of only small 3 Â 3 and 2 Â 2 domains, whose phases are shifted [4].…”