**4.2 100** f g **vertical side-surfaces**

**Figure 11(a)** shows a typical filtered RHEED pattern obtained from 3D Si with f g 100 side-surfaces. The 100 f g side-surfaces were created on a commercial mirrorpolished Si 100 ð Þ substrate (**Figure 6(a)**). In **Figure 11(a)** (*θ* = +0.4° and *ϕ* = �1.2°), the two overlapping Si 100 f g2�1 reconstructed diffraction patterns [4, 24] originated

**4. Surface structures on 3D architected Si sample**

**Figure 9(b)**–**(d)** show typical filtered RHEED patterns obtained from 3D Si with a vertical 111 f g side-surface (**Figure 7(c)**) various *θ* and *ϕ* values. The 111 f g side-surfaces were produced on a 110 ð Þ surface (**Figure 6(c)**). The RHEED patterns showed curious characteristics, because half of the patterns were removed, which has not been reported to the best of our knowledge. The appearance of the left-side

*Schematic of the diffraction from the top- and side-surfaces of a 3D patterned Si*ð Þ 110 *substrate. The control of the incident electron beam direction defined by* θ *and* ϕ *enables the observable faces in the 3D space to be*

*(a) Dependence of observable conditions (orange) in the RHEED pattern on the polarity of* θ *and* ϕ*. (b)–(d) RHEED patterns from 3D Si with* f g 111 *vertical side-surfaces observed at (b)* θ *= 0.0*° *and* ϕ *= +1.9*°*, (c)* θ *= +0.3*° *and* ϕ *=* �*1.6*°*, and (d)* θ *= +0.3*° *and* ϕ *= +1.1*°*. Insets schematically show the relationship between the*

*incident electron beam and the observable surfaces in 3D space.*

**4.1 111** f g **vertical side-surfaces**

*21st Century Surface Science - a Handbook*

**Figure 8.**

*selected.*

**Figure 9.**

**98**

#### **Figure 10.**

*LEED patterns for 3D Si sample with a wider* ð Þ 111 *side-surface at different incident angles of the electron beam with Ep = 80 eV: (a) normal incidence to the Si*ð Þ 111 *side-surface and (b)* �*37*° *tilted from the normal direction. The relationship between the incident beam and the sample and the simulated LEED patterns are shown in the upper and lower right, respectively.*

**4.3 110** f g **vertical side-surfaces**

*DOI: http://dx.doi.org/10.5772/intechopen.92860*

*at* θ *= +0.4*° *and* ϕ *=* �*1.2*°*.*

*<sup>L</sup>*ð Þ <sup>011</sup>

**Figure 11.**

*L* ð Þ <sup>011</sup> <sup>1</sup>*=*<sup>16</sup> to *L*

*a* ! <sup>∗</sup>

*a* ! <sup>∗</sup>

**101**

<sup>1</sup>*=*<sup>16</sup> , … .., *<sup>L</sup>*ð Þ <sup>011</sup>

*<sup>s</sup>* <sup>110</sup> ¼ 1*=*2*a*

*<sup>s</sup>* <sup>110</sup> ¼ 1*=*2*a*

ð Þ <sup>011</sup>

!<sup>∗</sup>

!<sup>∗</sup>

zone arc of Si 100 ð Þ of *<sup>L</sup>*ð Þ <sup>100</sup>

**4.4 111** f g **tilted facet-surfaces**

<sup>110</sup> and *b*

<sup>110</sup> and *b*

!<sup>∗</sup>

!<sup>∗</sup>

*<sup>s</sup>* <sup>110</sup> ¼ 1*=*16*a*

*<sup>s</sup>* <sup>110</sup> ¼ �1*=*16*a*

Finally, the RHEED pattern from the vertical 110 f g side-surface is shown in **Figure 12(a)**. Here, a 110 f g side-surface was produced on a 2D 100 ð Þ substrate (**Figure 6(b)**). **Figure 12(a)** shows the RHEED pattern from a 110 f g sample at *θ* = +0.4° and *ϕ* = +1.1°. A 110 f g16�2 pattern can be seen in the right quarter,

*(a) RHEED pattern from the 3D Si sample with vertical* f g 100 *side-surfaces at* θ *= +0.4*° *and* ϕ *=* �*1.2*°*. The inset shows the relationship between the incident electron beam and the 3D surfaces. (b) Schematics of the 2D reciprocal lattices on* f g 100 *2*�*1 reconstruction (left) and simulated RHEED pattern from the* f g 100 *surfaces*

*Creation and Evaluation of Atomically Ordered Side- and Facet-Surface Structures of Three…*

The weak spots in the arcs from the DB in the upper right, some of which are

rods. Here, the reconstructed surface unit vectors from Si 110 ð Þ2�16 are defined as

<sup>110</sup> þ 1*=*16*b*

<sup>110</sup> þ 1*=*16*b*

shown in **Figure 12(a)**. In **Figure 12(a)**, domain A is only considered as a 011 eye guide. The incident electron direction was the 011 ½ � direction, and the first Laue

<sup>1</sup> (**Figure 12(b)**) is the same as *L*

**Figure 13(a)** shows a typical filtered RHEED pattern obtained from the 111 f g facet sample at *θ*<sup>g</sup> = +0.7° and *ϕ* = +2.7° after flashing in UHV. The RHEED pattern showed notable characteristics, consisting of tilted 7�7 spots (some are marked by

<sup>1</sup> ) [24, 25] as shown in **Figure 12(c)**. The horizontal streaks from

<sup>1</sup> represent the diffractions from 00 ð Þ to 10 ð Þ at the reciprocal lattice

! <sup>∗</sup>

!<sup>∗</sup>

<sup>110</sup> (domain A, purple points) and

<sup>110</sup> (domain B, green points), as

<sup>1</sup> (**Figure 12(d)**).

ð Þ <sup>011</sup>

ð Þ <sup>011</sup> <sup>0</sup> ,

indicated by blue arcs, can be assigned to the Laue zone in the 011 plane (*L*

corresponding to the diffraction from the right-side 011 surface.

!<sup>∗</sup>

! <sup>∗</sup>

yellow circles, and 1/7th-order Laue zones, L1/7-L6/7, are recognized) and

from the top/bottom and left-side surfaces. One is a 100 ð Þ 2�1 pattern with a semicircular shape having a shadow edge SE(100) in the horizontal direction. The other is a 001 ð Þ 2�1 pattern on the left quarter side with a shadow edge SE(100) in the vertical direction.

We can see that the diffraction spots on the left side are slightly elongated in the horizontal direction, which is a characteristic of a RHEED pattern from a sidesurface [6]. The diffractions from the top-/bottom-surfaces disappeared and those from the left-side surface remained when we changed *θ* from +0.4° to 0.0°. When we set *θ* = +0.0° and *ϕ* = �1.2°, only a quarter circle 2�1 pattern with strong Kikuchi lines and bands can been seen, corresponding to the relationship between *θ* and *ϕ*, that is, the glancing and azimuth angles for each surface, respectively, similarly to that observed in **Figure 9(a)**. Quarter circle 2�1 patterns were also observed on the right when *ϕ* was positive.

The left part of **Figure 11(b)** shows the reciprocal lattice of the Si 100 f g2�1 reconstruction, corresponding to the left-side and top-/bottom-surfaces of the f g 100 sample. The 2D reciprocal lattice of Si 001 ð Þ is perpendicular to that of Si 100 ð Þ with the common crystalline direction of 010 . The Ewald constructions on the 100 ð Þ top/bottom and 001 ð Þ left-side surfaces in 3D reciprocal space in our experimental setup, namely, the simulated RHEED patterns at *θ* = +0.4° and *ϕ* = �1.2° (**Figure 11(b)** right panel), show good agreement with the observed RHEED pattern (**Figure 11(a)**). These results indicate that atomically flat side-surfaces were achieved on the 100 f g sample.

*Creation and Evaluation of Atomically Ordered Side- and Facet-Surface Structures of Three… DOI: http://dx.doi.org/10.5772/intechopen.92860*

#### **Figure 11.**

from the top/bottom and left-side surfaces. One is a 100 ð Þ 2�1 pattern with a semicircular shape having a shadow edge SE(100) in the horizontal direction. The other is a 001 ð Þ 2�1 pattern on the left quarter side with a shadow edge SE(100) in the vertical direction. We can see that the diffraction spots on the left side are slightly elongated in the

*LEED patterns for 3D Si sample with a wider* ð Þ 111 *side-surface at different incident angles of the electron beam with Ep = 80 eV: (a) normal incidence to the Si*ð Þ 111 *side-surface and (b)* �*37*° *tilted from the normal direction. The relationship between the incident beam and the sample and the simulated LEED patterns are*

horizontal direction, which is a characteristic of a RHEED pattern from a sidesurface [6]. The diffractions from the top-/bottom-surfaces disappeared and those from the left-side surface remained when we changed *θ* from +0.4° to 0.0°. When we set *θ* = +0.0° and *ϕ* = �1.2°, only a quarter circle 2�1 pattern with strong Kikuchi lines and bands can been seen, corresponding to the relationship between *θ* and *ϕ*, that is, the glancing and azimuth angles for each surface, respectively, similarly to that observed in **Figure 9(a)**. Quarter circle 2�1 patterns were also observed on the

The left part of **Figure 11(b)** shows the reciprocal lattice of the Si 100 f g2�1 reconstruction, corresponding to the left-side and top-/bottom-surfaces of the f g 100 sample. The 2D reciprocal lattice of Si 001 ð Þ is perpendicular to that of Si 100 ð Þ with the common crystalline direction of 010 . The Ewald constructions on the 100 ð Þ top/bottom and 001 ð Þ left-side surfaces in 3D reciprocal space in our experimental setup, namely, the simulated RHEED patterns at *θ* = +0.4° and *ϕ* = �1.2° (**Figure 11(b)** right panel), show good agreement with the observed RHEED pattern (**Figure 11(a)**). These results indicate that atomically flat side-surfaces were

right when *ϕ* was positive.

*shown in the upper and lower right, respectively.*

*21st Century Surface Science - a Handbook*

**Figure 10.**

achieved on the 100 f g sample.

**100**

*(a) RHEED pattern from the 3D Si sample with vertical* f g 100 *side-surfaces at* θ *= +0.4*° *and* ϕ *=* �*1.2*°*. The inset shows the relationship between the incident electron beam and the 3D surfaces. (b) Schematics of the 2D reciprocal lattices on* f g 100 *2*�*1 reconstruction (left) and simulated RHEED pattern from the* f g 100 *surfaces at* θ *= +0.4*° *and* ϕ *=* �*1.2*°*.*
