Dissolution suppression of self-assembled GaSb quantum dots on silicon by proper surface preparation

Abstract

The temperature stability of high-density GaSb quantum dots grown on a Si(111) surface using solid-phase epitaxy is investigated during annealing at 450 °C. It is found that the bare silicon surface plays a critical role in the GaSb decomposition through the destruction of Sb–Ga bonds with the simultaneous formation of Sb–Si bonds. GaSb decomposition can be significantly suppressed if saturated monolayer coverage in the form of the Si(111)-(√3 × √3)-R30°-Sb surface reconstruction is preliminarily formed. This allows GaSb quantum dots to be embedded in the silicon matrix using molecular beam epitaxy at high temperature.

Influence of the temperature and substrate modification on the formation of continuous GaSb film on Si(111) by solid phase epitaxy

“…In order to noticeably increase the size of GaSb nanocrystals in the film and to obtain epitaxial GaSb film, it was proposed to first form GaSb seed islands on the Si(111)7 × 7 surface, and then to deposit the GaSb mixture and anneal at the selected temperature as was previously performed in. 32) According to this work, the area of surface occupied by GaSb seed islands is 48.3%, and their concentration is 1.23 × 10 11 cm −2 .…”

“…To avoid the outflow of Sb atoms into surface reconstructions, sample D was made using GaSb seed islands on a preformed Sb surface reconstructions. 32) Corresponding LEED pattern [Fig. 5 for samples B and C. This indicates that the area of GaSb seed islands on sample D is noticeably larger than on samples B and C and at least greater than the coherence length of LEED electron beam.…”

“…In order to clarify whether GaSb seed islands grew epitaxially on Si(111), we grew them on Si(111) substrate as described in, 32) coated them with a Si layer to protect from oxidation, and then examined by high-resolution transmission electron microscopy (HRTEM). HRTEM image of a GaSb seed island on Si(111) is presented in Fig.…”

“…To increase the size of GaSb seed islands, we increased the thickness of the GaSb mixture used for their formation to 0.5 nm (samples D and E). During the formation of GaSb seed islands, some Sb atoms from the GaSb mixture are used to produce the Sb surface reconstructions (details could be found elsewhere 32) ). This leads to a decrease in the area of the GaSb seed islands.…”