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

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

The weak spots in the arcs from the DB in the upper right, some of which are indicated by blue arcs, can be assigned to the Laue zone in the 011 plane (*L* ð Þ <sup>011</sup> <sup>0</sup> , *<sup>L</sup>*ð Þ <sup>011</sup> <sup>1</sup>*=*<sup>16</sup> , … .., *<sup>L</sup>*ð Þ <sup>011</sup> <sup>1</sup> ) [24, 25] as shown in **Figure 12(c)**. The horizontal streaks from *L* ð Þ <sup>011</sup> <sup>1</sup>*=*<sup>16</sup> to *L* ð Þ <sup>011</sup> <sup>1</sup> represent the diffractions from 00 ð Þ to 10 ð Þ at the reciprocal lattice rods. Here, the reconstructed surface unit vectors from Si 110 ð Þ2�16 are defined as *a* ! <sup>∗</sup> *<sup>s</sup>* <sup>110</sup> ¼ 1*=*2*a* !<sup>∗</sup> <sup>110</sup> and *b* !<sup>∗</sup> *<sup>s</sup>* <sup>110</sup> ¼ 1*=*16*a* !<sup>∗</sup> <sup>110</sup> þ 1*=*16*b* ! <sup>∗</sup> <sup>110</sup> (domain A, purple points) and *a* ! <sup>∗</sup> *<sup>s</sup>* <sup>110</sup> ¼ 1*=*2*a* !<sup>∗</sup> <sup>110</sup> and *b* !<sup>∗</sup> *<sup>s</sup>* <sup>110</sup> ¼ �1*=*16*a* ! <sup>∗</sup> <sup>110</sup> þ 1*=*16*b* !<sup>∗</sup> <sup>110</sup> (domain B, green points), as 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 zone arc of Si 100 ð Þ of *<sup>L</sup>*ð Þ <sup>100</sup> <sup>1</sup> (**Figure 12(b)**) is the same as *L* ð Þ <sup>011</sup> <sup>1</sup> (**Figure 12(d)**).
