STM study of the Ga thin films grown on Si(111) surface

Gallenene epitaxially grown on Si(1 1 1)

“…The deposition of 1/3 monolayer (ML) Ga atoms and annealing subsequently at 550 °C lead to the formation of √ 3 × √ 3-Ga R30° surface reconstruction [20,21] (1 ML is defined as the density of a bulk truncated Si(1 1 1) surface which is 7.85 × 10 14 atoms cm −2 ). When the Ga coverage increases to 1 ML, various structures were observed by low energy electron diffraction (LEED) [21][22][23][24] and STM [20,[25][26][27], such as the phases of 6.3 × 6.3, 11 × 11, 6 √ 3 × 6 √ 3-R30° and 1 × 1. However, in the above reported studies, Ga atoms are all directly adsorbed on Si(1 1 1) − 7 × 7 and the structure of gallenene have not been found.…”

Few-monolayer Ga film on Si(111): illusive gallenene formation and localization instead of superconductivity

“…The procedure for growing the Ga atomic layers used in the present study was similar to that employed in ref. 17 and 18. As a starting template, the Si(111) surface was prepared using deposition of 1/3 ML of Ga (1 ML = 7.8 × 10 14 cm −2 ) onto the Si(111)7 × 7 surface at room temperature (RT) followed by annealing at ∼550 °C.…”

“…16 Returning to the Ga films, the Si(111) substrate terminated by ffiffiffi 3 p × ffiffiffi 3 p -Ga has recently been proved to be a template for the formation of uniform single-and doubleatomic-layer Ga films. 17,18 Seemingly, these Ga films could be expected to possess advanced superconducting properties, at least, due to the two reasons, as follows: the first is associated with their possible similarity to the above mentioned few-atomic-layer Ga films on GaN(0001) 6,7 and SiC(111); 8 the second reason stems from the recently reported findings that the top Ga layer in the Ga film on Si(111) shows up as gallenene, an analogue of graphene composed of gallium atoms, 18 which has been theoretically predicted to be a superconductor with T c in the range 7-10 K. 19 Occurrence of the gallenene is thought to be an independent subject, bearing in mind the recent research interest on the whole 2D-Xene family [20][21][22][23] and, in particular, gallenene. 18,19,[24][25][26][27] Motivated by these findings and predictions, we have considered Ga atomic films on Si(111), exploring their properties with particular emphasis on their structure and transport properties in an attempt to detect advanced superconductivity.…”