Structure and orientation of epitaxial titanium silicide nanowires determined by electron microdiffraction

Abstract

The crystal structure and epitaxial orientation of self-assembled titanium silicide nanowires (NWs) on Si (111) is determined using transmission electron microdiffraction. The NWs are formed by deposition of ∼1 monolayer Ti on Si(111) at ∼850 °C. Type 1 NWs are oriented with long axis along Si〈2-20〉 and are identified as C49 TiSi2. The most common orientation is C49 [01-3] || Si [112] and C49 (200) || Si (2-20), but several other orientations are also found. Type 2 NWs are oriented with long axis along Si〈224〉 and are identified as B27 TiSi, with orientation B27 [02-1] || Si [111] and B27 (-312) || Si (22-4) + 4°. Most of the NWs are incommensurate and fully strain relaxed. They generally extend below the surface with inclined incoherent interfaces.

Self-assembled epitaxial NiSi2 nanowires on Si(001) by reactive deposition epitaxy

“…A large number of self-assembled epitaxial silicide NWs were investigated in recent years [8][9][10][11][12][13][14][15][16]. The main focus on the study of these NWs has been on the rare-earth/Si and Ti/Si systems, based on the formation mechanism of strain-driven ''shape transition'', as represented by the Tersoff and Tromp and Jesson et al models [17,18].…”

Metal silicides: An integral part of microelectronics

“…A large number of self-assembled epitaxial silicide nanowires were investigated in the past. [36][37][38][39][40][41][42][43][44] Many RE silicide nanowires were grown on silicon substrates. These RE nanowires are commensurate with nearly perfect lattice match in their long direction and are limited in their ability to grow coherently 20 nm Figure 7.…”

“…45 On the other hand, for the growth of C49-TiSi 2 , the range of structural variants argues against a simple interface-energy explanation. 40 It is, however, interesting that TiSi 2 nanowires are incommensurate (8%) in their long direction. 46 However, the interface structure for the nanowires may not be the same as that inferred from the bulk lattices.…”

Formation of metal nano‐wires on heat‐treated substrates using an ultrahigh vacuum transmission electron microscope

“…A number of NWs have successfully been fabricated either by self-assembly 1 -4 or by top-down techniques. 5,6 Self-assembled NWs are well observed in epitaxial silicide/Si systems, where NW formation is promoted by the growth of a commensurate epitaxial layer with an anisotropy in lattice match with the substrates, 1,2 growth of incommensurate epitaxial layer with a low-energy interface, 3,4 and so on. At the same time, some materials that do not intermix at the interface with Si also form NWs, such as CaF 2 on Si (001) and Si (111) substrates.…”