Limits...
Nucleation and growth of primary nanostructures in SrTiO3 homoepitaxy.

Phark SH, Chang YJ - Nanoscale Res Lett (2015)

Bottom Line: Second, one-dimensional SrTiO3 islands of a 4 uc width grew along the crystal symmetry directions.These observations suggest that 4 × 4-uc (2) islands act as a minimum nucleation seed, and the addition of SrTiO3 molecular species of the same width is the primary and dominant growth process in SrTiO3 homoepitaxy.A close inspection of the surface of the substrate during the deposition process revealed possible connections between surface reconstruction and energetically favorable nucleation of SrTiO3 islands.

View Article: PubMed Central - PubMed

Affiliation: Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul National University, Seoul, 151-747 Republic of Korea ; Department of Physics and Astronomy, Seoul National University, Seoul, 151-747 Republic of Korea.

ABSTRACT
SrTiO3 nanoislands on SrTiO3 (001) in a diffusion-limited growth regime were studied using in situ scanning tunneling microscopy (STM). The STM images revealed two characteristic features of nucleation stages. First, the minimum lateral size of the one-unit-cell (uc)-high SrTiO3 islands was 4 × 4 uc (2). Second, one-dimensional SrTiO3 islands of a 4 uc width grew along the crystal symmetry directions. These observations suggest that 4 × 4-uc (2) islands act as a minimum nucleation seed, and the addition of SrTiO3 molecular species of the same width is the primary and dominant growth process in SrTiO3 homoepitaxy. A close inspection of the surface of the substrate during the deposition process revealed possible connections between surface reconstruction and energetically favorable nucleation of SrTiO3 islands.

No MeSH data available.


STM images for initial growth patterns in SrTiO3homoepitaxy. (a) and (b) 50 × 50-nm2 STM images of 1-p samples grown at 580°C and 620°C, respectively. (c) and (d) ((e) and (f)) 2-p (3-p) samples grown at 580°C and 620°C, respectively. All STM images were obtained with VS = 2.0 V and Iset = 50 pA. The green arrows indicate the smallest islands, which are 1 uc high. The yellow (cyan) arrows indicate 1D (2D) SrTiO3 islands. The inset of (a) shows a 7 × 7-nm2 STM image of a SrTiO3 island, as indicated by the green arrow. The gray arrows in (a), (b), and (e) indicate the substrate monatomic-high step edges.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4385118&req=5

Fig2: STM images for initial growth patterns in SrTiO3homoepitaxy. (a) and (b) 50 × 50-nm2 STM images of 1-p samples grown at 580°C and 620°C, respectively. (c) and (d) ((e) and (f)) 2-p (3-p) samples grown at 580°C and 620°C, respectively. All STM images were obtained with VS = 2.0 V and Iset = 50 pA. The green arrows indicate the smallest islands, which are 1 uc high. The yellow (cyan) arrows indicate 1D (2D) SrTiO3 islands. The inset of (a) shows a 7 × 7-nm2 STM image of a SrTiO3 island, as indicated by the green arrow. The gray arrows in (a), (b), and (e) indicate the substrate monatomic-high step edges.

Mentions: Figure 2a and 2b show images of SrTiO3 films following a single pulse (1-p) at Tsub = 580°C and 620°C, respectively. The images reveal the formation of SrTiO3 islands of extremely small size, with a height of 1 uc (≈0.39 nm). At Tsub = 580°C, most of the islands were square and uniform in size. The inset of Figure 2a shows a high-resolution STM image of the smallest SrTiO3 island observed in this study. All four sides of the island were parallel to the directions of the crystallographic base vectors, i.e., [100] and [010]. The length of each side was approximately 1.6 nm, corresponding to 4 uc; hence, we term such square islands 4 × 4-uc2 SrTiO3. We observed larger islands that were rod-shaped at Tsub = 620°C, as shown in Figure 2b. The longer side was several times the length of the shorter side and was parallel to the crystallographic axes; interestingly, the shorter side was 4-uc-long SrTiO3.Figure 2


Nucleation and growth of primary nanostructures in SrTiO3 homoepitaxy.

Phark SH, Chang YJ - Nanoscale Res Lett (2015)

STM images for initial growth patterns in SrTiO3homoepitaxy. (a) and (b) 50 × 50-nm2 STM images of 1-p samples grown at 580°C and 620°C, respectively. (c) and (d) ((e) and (f)) 2-p (3-p) samples grown at 580°C and 620°C, respectively. All STM images were obtained with VS = 2.0 V and Iset = 50 pA. The green arrows indicate the smallest islands, which are 1 uc high. The yellow (cyan) arrows indicate 1D (2D) SrTiO3 islands. The inset of (a) shows a 7 × 7-nm2 STM image of a SrTiO3 island, as indicated by the green arrow. The gray arrows in (a), (b), and (e) indicate the substrate monatomic-high step edges.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385118&req=5

Fig2: STM images for initial growth patterns in SrTiO3homoepitaxy. (a) and (b) 50 × 50-nm2 STM images of 1-p samples grown at 580°C and 620°C, respectively. (c) and (d) ((e) and (f)) 2-p (3-p) samples grown at 580°C and 620°C, respectively. All STM images were obtained with VS = 2.0 V and Iset = 50 pA. The green arrows indicate the smallest islands, which are 1 uc high. The yellow (cyan) arrows indicate 1D (2D) SrTiO3 islands. The inset of (a) shows a 7 × 7-nm2 STM image of a SrTiO3 island, as indicated by the green arrow. The gray arrows in (a), (b), and (e) indicate the substrate monatomic-high step edges.
Mentions: Figure 2a and 2b show images of SrTiO3 films following a single pulse (1-p) at Tsub = 580°C and 620°C, respectively. The images reveal the formation of SrTiO3 islands of extremely small size, with a height of 1 uc (≈0.39 nm). At Tsub = 580°C, most of the islands were square and uniform in size. The inset of Figure 2a shows a high-resolution STM image of the smallest SrTiO3 island observed in this study. All four sides of the island were parallel to the directions of the crystallographic base vectors, i.e., [100] and [010]. The length of each side was approximately 1.6 nm, corresponding to 4 uc; hence, we term such square islands 4 × 4-uc2 SrTiO3. We observed larger islands that were rod-shaped at Tsub = 620°C, as shown in Figure 2b. The longer side was several times the length of the shorter side and was parallel to the crystallographic axes; interestingly, the shorter side was 4-uc-long SrTiO3.Figure 2

Bottom Line: Second, one-dimensional SrTiO3 islands of a 4 uc width grew along the crystal symmetry directions.These observations suggest that 4 × 4-uc (2) islands act as a minimum nucleation seed, and the addition of SrTiO3 molecular species of the same width is the primary and dominant growth process in SrTiO3 homoepitaxy.A close inspection of the surface of the substrate during the deposition process revealed possible connections between surface reconstruction and energetically favorable nucleation of SrTiO3 islands.

View Article: PubMed Central - PubMed

Affiliation: Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul National University, Seoul, 151-747 Republic of Korea ; Department of Physics and Astronomy, Seoul National University, Seoul, 151-747 Republic of Korea.

ABSTRACT
SrTiO3 nanoislands on SrTiO3 (001) in a diffusion-limited growth regime were studied using in situ scanning tunneling microscopy (STM). The STM images revealed two characteristic features of nucleation stages. First, the minimum lateral size of the one-unit-cell (uc)-high SrTiO3 islands was 4 × 4 uc (2). Second, one-dimensional SrTiO3 islands of a 4 uc width grew along the crystal symmetry directions. These observations suggest that 4 × 4-uc (2) islands act as a minimum nucleation seed, and the addition of SrTiO3 molecular species of the same width is the primary and dominant growth process in SrTiO3 homoepitaxy. A close inspection of the surface of the substrate during the deposition process revealed possible connections between surface reconstruction and energetically favorable nucleation of SrTiO3 islands.

No MeSH data available.