ABSTRACT The growth morphology of iron on Au(788) has been investigated from 45K to 430K by use o... more ABSTRACT The growth morphology of iron on Au(788) has been investigated from 45K to 430K by use of variable temperature scanning tunneling microscopy. This system displays an ordered growth regime of a nanodots array from 70K to 300K (room temperature, RT). According to the temperature, the dots are found to grow on two different sites: below 250K, they form rounded isolated islands above the steps where local traps act as nucleation centers; from 250K to 300K, they have the shape of platelets regularly disposed along the bottom of the step edges and located on face centered cubic area of the Au(788) surface reconstruction. Above RT, as a function of temperature, we find a progressive transition of the growth morphology, from ordered platelets to a step flow growth. A surface alloy formation induced by the high step density is the driving force of this growth mode transition.
ABSTRACT The present scanning tunneling microscopy study reports on the growth processes of Co va... more ABSTRACT The present scanning tunneling microscopy study reports on the growth processes of Co vapor-deposited on a dodecanethiol (DDT) self-assembled monolayer (SAM)/Au(111). We observe strongly modified surface and depth diffusions of Co adatoms depending on the growth temperature. Co deposited at 300 K shows an extremely incomplete regime of condensation on the organic layer. Besides, Co penetrates the DDT monolayer and resides at the DDT/Au(111) interface as 2D clusters. This phenomenon takes place through defects in the SAM which are transient channels. In contrast, Co deposited at 50 K shows a complete condensation and nucleates on defects of the SAM layer as 3D islands sitting most likely on top of the DDTs. These results are of interest in the growing field of organic spintronics where the quality of the organic/ferromagnetic interface is a key issue.
Thermal energy atom scattering on vacuum deposited Pb submonolayers on Cu(111) in close to equili... more Thermal energy atom scattering on vacuum deposited Pb submonolayers on Cu(111) in close to equilibrium conditions, at substrate temperatures between 303 K and 413 K, gives evidence for: (a) decoration by Pb atoms of monatomic steps on the Cu surface at degree of coverage 0 < θ < 0.004; (b) formation of disordered surface alloy in the first lattice plane of the copper substrate in the coverage range 0.004 < θ < 0.21; (c) formation of non-alloyed Pb layer with a p(4 × 4) structure above this coverage, up to the monolayer (θ ≈ 0.56). The latter transition is shown to be of first order. The role of the deposition kinetics in far from equilibrium conditions is pointed out.
ABSTRACT The growth morphology of iron on Au(788) has been investigated from 45K to 430K by use o... more ABSTRACT The growth morphology of iron on Au(788) has been investigated from 45K to 430K by use of variable temperature scanning tunneling microscopy. This system displays an ordered growth regime of a nanodots array from 70K to 300K (room temperature, RT). According to the temperature, the dots are found to grow on two different sites: below 250K, they form rounded isolated islands above the steps where local traps act as nucleation centers; from 250K to 300K, they have the shape of platelets regularly disposed along the bottom of the step edges and located on face centered cubic area of the Au(788) surface reconstruction. Above RT, as a function of temperature, we find a progressive transition of the growth morphology, from ordered platelets to a step flow growth. A surface alloy formation induced by the high step density is the driving force of this growth mode transition.
ABSTRACT The present scanning tunneling microscopy study reports on the growth processes of Co va... more ABSTRACT The present scanning tunneling microscopy study reports on the growth processes of Co vapor-deposited on a dodecanethiol (DDT) self-assembled monolayer (SAM)/Au(111). We observe strongly modified surface and depth diffusions of Co adatoms depending on the growth temperature. Co deposited at 300 K shows an extremely incomplete regime of condensation on the organic layer. Besides, Co penetrates the DDT monolayer and resides at the DDT/Au(111) interface as 2D clusters. This phenomenon takes place through defects in the SAM which are transient channels. In contrast, Co deposited at 50 K shows a complete condensation and nucleates on defects of the SAM layer as 3D islands sitting most likely on top of the DDTs. These results are of interest in the growing field of organic spintronics where the quality of the organic/ferromagnetic interface is a key issue.
Thermal energy atom scattering on vacuum deposited Pb submonolayers on Cu(111) in close to equili... more Thermal energy atom scattering on vacuum deposited Pb submonolayers on Cu(111) in close to equilibrium conditions, at substrate temperatures between 303 K and 413 K, gives evidence for: (a) decoration by Pb atoms of monatomic steps on the Cu surface at degree of coverage 0 < θ < 0.004; (b) formation of disordered surface alloy in the first lattice plane of the copper substrate in the coverage range 0.004 < θ < 0.21; (c) formation of non-alloyed Pb layer with a p(4 × 4) structure above this coverage, up to the monolayer (θ ≈ 0.56). The latter transition is shown to be of first order. The role of the deposition kinetics in far from equilibrium conditions is pointed out.
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Papers by Yann Girard