Strong asymmetric effect of lattice mismatch on epilayer structure in thin-film deposition

Abstract

We investigate the heteroepitaxial growth of thin film deposited on a ͑001͒ substrate via molecular-dynamics simulations, using six fcc transition metals as our modeling systems. By studying the radial distribution function in the film layers, we demonstrate the importance of the sign of lattice mismatch on the layer structure. For positive lattice mismatches, the film favors pseudomorphic growth, whereas for negative mismatches, a sharp transition happens within the first few monolayers of adatoms and the film layers are transformed into the close-packed ͑111͒ structure. We propose a way to quantify the compositional percentage of different planar structures in an epilayer and demonstrate the strong asymmetric effect between the tensile and compressive cases of deposition. How temperature affects the asymmetry is also discussed.

Origin of an unusual systematic variation in the heteroepitaxy of Ag on Ni – The roles of twinning and step alignment

“…The range of rotations from OR T to OR O is given by the twin lattice correspondence alone and is thus valid for all heteroepitaxial systems, independent of lattice parameter ratio. This explains why the same ORs are found in a number of heteroepitaxial systems [34]. However, the eigenvalues depend directly on the lattice parameters, and since only small strains (eigenvalues close to =1) can be accommodated in the interface, it is not unreasonable that only a limited range of systems exhibits OR O.…”

“…While it has been known for some time that Ag equilibrated on Ni(100) adopts a (111) interfacial orientation, i.e. the so-called oct-cube OR (OR O) [38], it has been shown more recently that this OR prevails in other FCC-on-FCC systems where the deposit possesses a lattice constant that is larger than that of the substrate by more than about 10% [34]. What our previous work [11,12,20] has uncovered is that there also exists an infinite set of "special" ORs (OR S) that develop as a transition from OR T, which prevails on Ni substrates oriented along the (111) to (210) line of the SST, to OR O at Ni(100).…”

Importance of interfacial step alignment in hetero-epitaxy and orientation relationships: the case of Ag equilibrated on Ni substrates. Part 2 experiments

“…The purpose of this paper is to determine the origins of the orientation relationships (ORs) obtained by equilibrating a deposit of one face centered cubic (FCC) metal on a substrate of a different FCC metal. The literature contains reports of experimental and modeling studies of several such FCC A-on-B systems, including Ag on Ni [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16], Ni on Ag [17], Au on Cu [11], Pb on Cu [18], Pb on Ni [19]. Thus far, experimental investigations have focused on B-substrates with low-index surfaces oriented along (111) and (100) crystallographic planes.…”

“…In contrast, on B(100), either a cube-on-cube OR with A(100)//B(100), or a so-called oct-cube OR with A(111)//B(100), has been reported [6,13]. Furthermore, the results of some simulations have indicated that the oct-cube OR is more likely when the atomic size of the A-component is much larger than that of the B-component [17]. For Ag on a Ni (110) substrate, Allameh et al [11] report a cube-on-cube OR.…”

Heat conduction across a solid-solid interface: Understanding nanoscale interfacial effects on thermal resistance

“…It includes a 10.0 nm  2.5 nm  2.5 nm solid Si lattice extending from 0-10 nm along the x-wise direction and a 10.0 nm  2.5 nm  2.5 nm Ge lattice from 10-20 nm. We neglect lattice mismatch during the epitaxial growth of Si films on Ge, or vice versa, which can influence interfacial thermal transport 15,16 and consider idealized defect-free Si-Ge interfaces that have smooth contacts.…”