Study of Initial Growth Layer of GaSb on Si(111) by Scanning Tunneling Microscopy

Abstract

The initial growth layer of GaSb on a Si(111) surface has been studied by scanning tunneling microscopy. After the simultaneous deposition of Ga and Sb atoms at 0.85 and 1.45 monolayers, respectively, Sb/Si(111)-2×1 and -√3×√3-R30° structures were formed on a large area of the Si(111) surface. In addition, the protrusions of the cross-hatch pattern, which was higher than that of the Sb/Si(111) structures by a bilayer height, were observed. The pattern area is suggested to correspond to the initial growth layer of GaSb. Three types of layer domains were observed. These domains are formed because of the strain caused by the lattice mismatch between GaSb and Si. Based on both cases of group-III and -V polar surface structures, the atomic structural models of these domains are proposed: one domain is a layer with strain relaxation, formed by the reconstruction of on-top atoms; the second is a layer formed on the reconstructed Si surface; and the third is a layer with uniaxial strain relaxation. Three-dimensional hut-shaped islands were observed to form infrequently on the local surface area. A cross-hatch pattern similar to the initial growth layer was observed on the facets of these islands. It is suggested that the islands are composed of GaSb crystals. An initial growth layer of GaSb was observed around some of the islands. From these results, we speculate that the GaSb dot crystals grow epitaxially on the initial layer.

Growth mechanism and structure characterizations of GaSb islands grown on Si (100) substrates by LP-MOCVD

“…In the initial stages, GaSb adatoms absorbed on the substrates and constructed a thin wetting layer [17]. With the large mismatch between GaSb and Si ($12.2%), the islands emerged with the strains released in the wetting layer [18].…”

Effect of Types of Ga/Si(111) Reconstructed Structure on Growth Morphology of GaSb Island

“…The cross-hatched pattern was also observed at the lower terrace. The zigzag line pattern and cross-hatched pattern correspond to the Sb/Si(111)-2×1 reconstructed structure and initial GaSb layer, respectively [14,16]. These results indicate that the initial GaSb layer is formed by the reaction between Ga atoms deposited on the surface and adsorbed Sb atoms.…”

“…Although the 2D layer was also observed as the result of slightly increase of the coverage [Fig. 3(b)], the high 2D islands with ordered protrusions were locally formed [inset in The 2D layer composed of a disordered pattern with the inverted triangular protrusions corresponds to the initial GaSb layer [14,15]. On the Si(111) surface, GaSb grows up to second layer with same pattern.…”

Study of GaSb Layers Grown on Ga/Si(111)-√3×√3 by Scanning Tunneling Microscopy

“…In previous works, the coexisting surface state of the initial GaSb layer and Sb/Si(111) was formed as a result of the simultaneous deposition of Ga and Sb atoms on clean Si(111). 14) Under such an experimental condition, the initial GaSb layer was formed on the local surface area. The formation area of the initial growth layer could expand over the entire surface in growth on Ga-terminated Si(111) [Ga/ Si(111)-ffiffi ffi…”

“…]. 15) However, the surface morphology of GaSb grown on Sb-terminated Si(111) [Sb/Si(111)-d7 Â 7 and Sb/Si(111)-2 Â 1] was roughened by the presence of the amorphous islands and the local higher two-dimensional island. 15) Therefore, it might be possible to develop a new GaSb nanostructure growth and fabrication technique using the initial GaSb layer on Ga/Si(111)-ffiffi ffi…”