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Temperature-Dependent Site Control of InAs/GaAs (001) Quantum Dots Using a Scanning Tunneling Microscopy Tip During Growth.

Toujyou T, Tsukamoto S - Nanoscale Res Lett (2010)

Bottom Line: However, these dots were remained at least 40 s and collapsed less than 1000 s.Then, we fabricated InAs nano dots (width: 24-150 nm, height: 2.8-28 nm) at 300°C under In and As(4) irradiations.These were not collapsed and considered to high crystalline dots.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Collaborative Research, Anan National College of Technology, Anan, Tokushima, 774-0017 Japan.

ABSTRACT
Site-controlled InAs nano dots were successfully fabricated by a STMBE system (in situ scanning tunneling microscopy during molecular beam epitaxy growth) at substrate temperatures from 50 to 430°C. After 1.5 ML of the InAs wetting layer (WL) growth by ordinal Stranski-Krastanov dot fabrication procedures, we applied voltage at particular sites on the InAs WL, creating the site where In atoms, which were migrating on the WL, favored to congregate. At 240°C, InAs nano dots (width: 20-40 nm, height: 1.5-2.0 nm) were fabricated. At 430°C, InAs nano dots (width: 16-20 nm, height: 0.75-1.5 nm) were also fabricated. However, these dots were remained at least 40 s and collapsed less than 1000 s. Then, we fabricated InAs nano dots (width: 24-150 nm, height: 2.8-28 nm) at 300°C under In and As(4) irradiations. These were not collapsed and considered to high crystalline dots.

No MeSH data available.


In situ STM images of surface structure transitions on the InAs WL by applying voltage at the particular sites (substrate temperature: 430°C). Whitecircles indicate hole structures, using it as markers for confirming the same position. a Before, b and c during applying voltages, d dot structures were appeared as indicated by whitearrows, and e these dots were collapsed
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Figure 3: In situ STM images of surface structure transitions on the InAs WL by applying voltage at the particular sites (substrate temperature: 430°C). Whitecircles indicate hole structures, using it as markers for confirming the same position. a Before, b and c during applying voltages, d dot structures were appeared as indicated by whitearrows, and e these dots were collapsed

Mentions: In order to increase crystal quality of nano structure, we tried to fabricate at 430°C under As4 irradiation. After the InAs WL growth at 500°C, a substrate temperature has decreased to 430°C under As4 irradiation. When the substrate temperature was stabilized, the STM units were combined and immediately started in situ STM observation. A tip bias was −0.2 V, a tunneling current was 0.4 nA, and the scan speed was 1,000 nm/s. After eliminating the thermal drift, we applied voltage from −0.4 to +0.4 V. White circles shown in Fig. 3 indicate hole structures (width: 15–18 nm, depth: 0.9–1.1 nm), using it as markers for confirming a same position. By the repetition of applying voltage as shown in Fig. 3b, 3c, five dot structures (width: 16–20 nm, height: 0.75–1.5 nm) were appeared as indicated the white arrows in Fig. 3d. But, these structures were disappeared at the subsequent image shown in Fig. 3e, these only remained at least 40 s and collapsed less than 1000 s. We consider that the collapse of the dot structures were caused by the high mobility of In atoms at this temperature [11-14].


Temperature-Dependent Site Control of InAs/GaAs (001) Quantum Dots Using a Scanning Tunneling Microscopy Tip During Growth.

Toujyou T, Tsukamoto S - Nanoscale Res Lett (2010)

In situ STM images of surface structure transitions on the InAs WL by applying voltage at the particular sites (substrate temperature: 430°C). Whitecircles indicate hole structures, using it as markers for confirming the same position. a Before, b and c during applying voltages, d dot structures were appeared as indicated by whitearrows, and e these dots were collapsed
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2991147&req=5

Figure 3: In situ STM images of surface structure transitions on the InAs WL by applying voltage at the particular sites (substrate temperature: 430°C). Whitecircles indicate hole structures, using it as markers for confirming the same position. a Before, b and c during applying voltages, d dot structures were appeared as indicated by whitearrows, and e these dots were collapsed
Mentions: In order to increase crystal quality of nano structure, we tried to fabricate at 430°C under As4 irradiation. After the InAs WL growth at 500°C, a substrate temperature has decreased to 430°C under As4 irradiation. When the substrate temperature was stabilized, the STM units were combined and immediately started in situ STM observation. A tip bias was −0.2 V, a tunneling current was 0.4 nA, and the scan speed was 1,000 nm/s. After eliminating the thermal drift, we applied voltage from −0.4 to +0.4 V. White circles shown in Fig. 3 indicate hole structures (width: 15–18 nm, depth: 0.9–1.1 nm), using it as markers for confirming a same position. By the repetition of applying voltage as shown in Fig. 3b, 3c, five dot structures (width: 16–20 nm, height: 0.75–1.5 nm) were appeared as indicated the white arrows in Fig. 3d. But, these structures were disappeared at the subsequent image shown in Fig. 3e, these only remained at least 40 s and collapsed less than 1000 s. We consider that the collapse of the dot structures were caused by the high mobility of In atoms at this temperature [11-14].

Bottom Line: However, these dots were remained at least 40 s and collapsed less than 1000 s.Then, we fabricated InAs nano dots (width: 24-150 nm, height: 2.8-28 nm) at 300°C under In and As(4) irradiations.These were not collapsed and considered to high crystalline dots.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Collaborative Research, Anan National College of Technology, Anan, Tokushima, 774-0017 Japan.

ABSTRACT
Site-controlled InAs nano dots were successfully fabricated by a STMBE system (in situ scanning tunneling microscopy during molecular beam epitaxy growth) at substrate temperatures from 50 to 430°C. After 1.5 ML of the InAs wetting layer (WL) growth by ordinal Stranski-Krastanov dot fabrication procedures, we applied voltage at particular sites on the InAs WL, creating the site where In atoms, which were migrating on the WL, favored to congregate. At 240°C, InAs nano dots (width: 20-40 nm, height: 1.5-2.0 nm) were fabricated. At 430°C, InAs nano dots (width: 16-20 nm, height: 0.75-1.5 nm) were also fabricated. However, these dots were remained at least 40 s and collapsed less than 1000 s. Then, we fabricated InAs nano dots (width: 24-150 nm, height: 2.8-28 nm) at 300°C under In and As(4) irradiations. These were not collapsed and considered to high crystalline dots.

No MeSH data available.