Characterization of strain in crystal bilayers using ion-channeling patterns

Abstract

This paper describes the experimental and theoretical simulation, the observation and the quantification of strain present in crystal bilayers using ion-channeling patterns produced by a focused 3 MeV proton beam. The dechanneling effects of strain are first experimentally simulated using different rotation angles between two individual, 0.3-m-thick, ͓100͔ silicon crystals. The patterns produced when both crystals are aligned close to the ͓100͔ axis, with a small rotation angle at the interface, are considered in detail using Monte Carlo computer simulations. Previously unobserved effects occurring in channeling patterns are discussed and general conditions under which different behavior is observed are described. Channeling patterns recorded through a thinned Si 0.85 Ge 0.15 /Si crystal bilayer are then used to characterize the interface rotation angle along several off-normal axes.

Confirmation of proton beam bending in graded Si1−xGex/Si layers using ion channeling

“…In the case of uniform heteroepitaxial Si 1Ϫx Ge x /Si bilayer structures, a layer of constant Ge concentration x is grown on a Si substrate and an interface rotation ͑''kink''͒ angle ⌬ is measured. 9 Depth-resolved angular channeling scans from such samples reveal an epilayer surface channeling dip displaced from the substrate dip by ⌬. 10 These alignments are illustrated in Figs.…”

Strain detection in crystalline heterostructures using bidimensional blocking patterns of channelled particles

“…Thus, a shift in the tilt angle from the layer and the substrate is expected when performing an angular scan (figure 1(b)). This shift is known as the kink angle δ and is given by δ = θ film − θ subs [34]. The tetragonal strain (ε T ) can then be obtained from δ because the geometrical relations between the lattice parameters and the tilt angle are well-known [35].…”

Planar Channelling Criticalities of MeV Protons in Si Crystal: Simulations, Evaluation and Applications

“…Coherent protons near space and phase criticalities during channelling are very sensitive to lattice disorders (translation and rotation). Changes in the channelled beam due to lattice translations at varying depth can be used to understand the structure of stacking faults, [16] whereas changes due to lattice rotations are helpful to model the interface rotation in bilayers [25] superlattices. [18] Figures 4(a) and 4(b) show, respectively, the phase and space criticality conditions using phase-space model and simulations with the help of computer code FLUX for proton planar channelling corresponding to two specific depths into Si crystal along {110} planes (see Table 2 for definition of criticality conditions).…”