Effect of Laser Beam Profile on Rotating Lattice Single Crystal Growth in Sb2S3 Model Glass

Abstract

Laser heating of chalcogenide glasses has successfully produced rotating lattice single crystals through a solid-solid transformation. To better understand the nature of complex, orientation-dependent lattice rotation, we designed heat profiles of the continuous wave laser by beam shaping, fabricated larger Sb2S3 crystal dots in Sb2S3 glass, and investigated the lattice rotation where the crystal could grow in all radial directions under a circular thermal gradient. The results show that the rate of lattice rotation is highly anisotropic and depends on crystallographic direction. The nature of this rotation is the same in crystals of different orientation relative to the surface. The growth directions that align with the slip planes show the highest rate of rotation and the rotation rate gradually decreases away from this direction. Additionally, the presence of multiple growth directions results in a complicated rotation system. We suggest that the growth front influences the density of dislocations introduced during growth under confinement and thus affects the lattice rotation rate in these crystals.

Curved lattices of crystals formed in glass

“…[94], with the permission of AIP Publishing is an indicator of the gradual change in lattice orientation from the crystal center toward its edge. If we generalize our coordinate system presented earlier by redefining the 3-axis to any localized heat source (electron beam in this case), then transrotational crystals have both nonzero 𝜅 21 and 𝜅 12 components just like the Sb 2 S 3 RLS crystal dots made using laser heating by Au-Yeung et al 34 Bagmut et al 95 grew Sb 2 S 3 needles via electron beam heating along the length of previously nucleated seeds. Although the orientation of the needles cannot be controlled, we can still define the 1-axis along their length.…”

“…Reprinted from ref. [34] this periodic structure was due to spiral crystal growth about the [110] axis. Figure 8A shows an example of this periodic domain structure fabricated with 1300 mW power cw Yb:YVO 4 fiber laser scanned at 5 μm/s.…”

“…The ambiguity between multiple growth directions becomes exacerbated for the case of radial crystal growth of dots shown in Figure 7B with either lattice curvature component ranging between 0.2 • /μm and 1.1 • /μm. 34 The choice of the 1-and 2-axes becomes arbitrary in this radially symmetric crystal, but the underlying cause and mechanism governing lattice curvature likely remain the same as for 1D RLS crystal lines.…”

“…Changing the laser scanning direction changes the crystal growth direction, and the direction of lattice curvature, as if the previous crystal line were a seed 30,32 . Changing this crystal growth direction relative to the lattice orientation can further affect the magnitude of lattice curvature shown in Figure 6 33,34 . The orientation dependence of lattice rotation rate indicates that intrinsic crystallographic tendencies as well as the laser parameters affect the resulting lattice curvature.…”

“…30,32 Changing this crystal growth direction relative to the lattice orientation can further affect the magnitude of lattice curvature shown in Figure 6. 33,34 The orientation dependence of lattice rotation rate indicates that intrinsic crystallographic tendencies as well as the laser parameters affect the resulting lattice curvature. Lattice engineered crystals are not limited to only lines in glass.…”