Figure 1

(Color online) (a) Laue spots measured at $21°\text{C}$ by a micro-x-ray beam. Strong spots are from the $\left(10\overline{1}0\right)$ ${\text{Al}}_2{\text{O}}_3$ substrate, and the weak spots in the box come from the ${\text{VO}}_2$ film. (b) An enlarged image of the box in Fig. 1a. ${\text{VO}}_2$ spots circled by red dots are indexed. The reference ${\text{Al}}_2{\text{O}}_3$ spot is denoted by $S$. (c) An enlarged image of the ${\text{VO}}_2$ spot measured at $70°\text{C}$. (d) Scanned intensity taken from A to B in the box of Fig. 1a. A strong spot near A is one of the substrate spots and a weak spot near B is one of the center spots coming from the ${\text{VO}}_2$ film. The reference ${\text{Al}}_2{\text{O}}_3$ spots do not move with temperature. (e) Enlarged image of the center spot, $\left(6,-10,-7\right)$, in the monoclinic structure at $21°\text{C}$. (f) Enlarged image of the center spot in the tetragonal structure at $70°\text{C}$. The position difference between two center spots is shown in Figs. 1e, 1f.Reuse & Permissions

Figure 2

(a) (Color online) A schematic diagram of the simulation configuration of x-ray microdiffraction. (b) A computer-calculated Laue pattern of a tilted (011) ${\text{VO}}_2$ plane with a $37°$ slope along the x axis. The vertical y direction is $\left[\overline{2}10\right]$. Spots in the blue boxed area are similar to those in the box of Fig. 1a. The simulation parameters of ${\text{VO}}_2$, $a=5.7520\text{Å}$, $b=4.5380\text{Å}$, and $c=5.3830\text{Å}$, a monoclinic angle of $\beta =122.60°$, and space group P121/c 1(14)-monoclinic were used. (c) A computer-calculated Laue pattern of the $\left(10\overline{1}0\right)$ ${\text{Al}}_2{\text{O}}_3$ substrate with a $\left[1\overline{1}0\right]$ vertical direction to the $y$ axis. The only blue boxed area in (b) overlaps the simulated ${\text{Al}}_2{\text{O}}_3$ Laue pattern to compare with the true image of Fig. 1a.Reuse & Permissions

Figure 3

(Color online) Inset: A microsurface image of the device with a length of $10\mu \text{m}$ and a width of $3\mu \text{m}$ after finishing experiments. The micro-x-ray beam was focused on the center of the ${\text{VO}}_2$ film. The uniform black marks to the cross-sectional direction at both electrode sides translate to burned photoresists by high currents; this is evidence of the absence of the current path (breakdown). $I\text{−}V$ sweeps for the device were simultaneously measured with micro-x-ray diffraction experiments. ${\text{V}}_{\text{MIT}}$ is 4.2 V at the jump. The micro-x-ray measurements were carried out at voltages of 0, 4, 5, 7, 8, and 10 V.Reuse & Permissions

Figure 4

(Color online) Voltage dependence of Laue patterns measured at voltage values denoted in Fig. 3. In (a)–(f), the strong Laue spots arise from the ${\text{Al}}_2{\text{O}}_3$ substrate, and weak spots come from the ${\text{VO}}_2$ film. (g) Intensity changes of P1, P2, P3, P4, M, and T spots denoted in (a)–(f) with increasing voltage to constant intensity of substrate spots. (h) A scanned image through the center spots from A to B as indicated in (a). (i)–(l) Enlarged images near the center spots. (k) and (l) show the positional difference between the center spots.Reuse & Permissions