Formation and crystallographic orientation of NiSi2–Si interfaces

Abstract

The transport properties of novel device architectures depend strongly on the morphology and the quality of the interface between contact and channel materials. In silicon nanowires with nickel silicide contacts, NiSi2–Si interfaces are particularly important as NiSi2 is often found as the phase adjacent to the silicide–silicon interface during and after the silicidation. The interface orientation of these NiSi2–Si interfaces as well as the ability to create abrupt and flat interfaces, ultimately with atomic sharpness, is essential for the properties of diverse emerging device concepts. We present a combined experimental and theoretical study on NiSi2–Si interfaces. Interfaces in silicon nanowires were fabricated using silicidation and characterized by high-resolution (scanning) transmission electron microscopy. It is found that {111} interfaces occur in ⟨110⟩ nanowires. A tilted interface and an arrow-shaped interface are observed, which depends on the nanowire diameter. We have further modeled NiSi2–Si interfaces by density functional theory. Different crystallographic orientations and interface variations, e.g., due to interface reconstruction, are compared with respect to interface energy densities. The {111} interface is energetically most favorable, which explains the experimental observations. Possible ways to control the interface type are discussed.

Reconfigurable Complementary and Combinational Logic Based on Monolithic and Single‐Crystalline Al‐Si Heterostructures

“…[ 33,39 ] For RFETs and other emerging devices an accurate control of phase formation becomes necessary as different phases and related lattice strain yield a variability in barrier heights and thus in the electronic injection properties. [ 40 ] Further on, phase instabilities lead to a junction patchiness that translates into additional variability of electrical performance. [ 41 ] Indeed, commonly employed metal‐silicides make the addition of further alloying elements such as for example, Pt or Sn in nickel‐silicides necessary to improve morphology and stabilize crystallographic phases.…”

Density Functional Investigation of [001] and [111] SiNWs and the Effect of Doping with Boron and Phosphorus

“…Therefore, SiNWs with relatively small diameters revealed anisotropic emerging electronic properties; these are quite interesting, given the industrial need for device miniaturization and the strong correlation between physical properties and sample sizes [25]. Specifically, this finding was in line with the synthesis of ultra-thin [001] SiNWs with diameters between 1.3 nm to 7 nm via an oxideassisted growth method, in which SiO powder was heated to 1200 • C in an alumina tube by Ma et al [27] or with transport measurements on SiNWs created along the [100], [111], or [110] directions [28].…”

Controlled Silicidation of Silicon Nanowires Using Flash Lamp Annealing

“…In Schottky-barrier-FETs (SBFETs), the Schottky barrier height and interface quality depend on the phase of the silicide adjacent to the Si channel. 1,39 In this context, NiSi 2 is of special interest for SBFETs, as its Fermi level is near mid-gap in relation to the Si bandgap.…”

“…In Schottky barrier FETs (SBFETs), the Schottky barrier height and interface quality depend on the phase of the silicide adjacent to the Si channel. , In this context, NiSi 2 is of special interest for SBFETs, as its Fermi level is near midgap in relation to the Si bandgap. Moreover, it has a small lattice mismatch with Si, enabling the formation of an atomically abrupt Si–NiSi 2 interface with good crystalline quality. , In planar thin-film reactions, Tu et al reported the formation of NiSi 2 above 750 °C, while Tung et al demonstrated its formation at 450 °C.…”