Thermal effects in the size distribution of SiC nanodots on Si(111)

Flores, Marcelo; Fuenzalida, V.M.; Häberle, Patricio

doi:10.1002/pssa.200420064

Cited by 14 publications

(3 citation statements)

References 23 publications

(12 reference statements)

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“…Not only will this process eventually lead to the complete decomposition of the oxide layer, it will also trigger a substantial roughening of the silicon surface itself, leading to the formation and growth of nanostructures at the initial void nucleation points in the oxide [3]. These nanostructures have been shown to grow in the form of silicon carbide (SiC) nanocrystals [4,5], which nucleate on the surface as a result of carbon contamination both from residual molecules in the vacuum chamber as well as impurity inclusions within the oxide [6].…”

Section: Introductionmentioning

confidence: 99%

Ordered array of self-assembled SiC nanocrystals fabricated by selective oxide desorption and nanosphere lithography

Hopf¹,

Leveneur²,

Markwitz³

2010

Nanotechnology

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We have developed a novel technique based on the selective desorption of an oxide film in order to grow ordered arrays of silicon carbide nanocrystals on a silicon surface. These nanocrystals form as a byproduct of void nucleation in the oxide during the high-temperature vacuum annealing of silicon, a process which normally produces a random distribution of nanocrystals across the silicon surface after its oxide layer has been fully desorbed. By the pre-deposition of a thin layer of excess silicon on the oxide surface through a patterned lithography mask, site-specific nucleation of voids in the silicon oxide can instead be achieved during the annealing step, leading to the growth of silicon carbide nanocrystals in regular patterns over the silicon surface.

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Section: Introductionmentioning

confidence: 99%

Ordered array of self-assembled SiC nanocrystals fabricated by selective oxide desorption and nanosphere lithography

Hopf¹,

Leveneur²,

Markwitz³

2010

Nanotechnology

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“…Several groups have attempted to synthesize SiC nanoparticles on wafers [4,5,9,10]. Xu et al [4] used RF plasma sputtering and a compound SiC target (Si:C ∼ 1:1) to deposit SiC nanoparticles on Si(100) substrates with AlN buffer layers at a substrate temperature of 350 • C for 1.0 h. Xu et al [5] applied low-energy mass-selected ion beam deposition (MSIBD) to select C + ions at 100 eV to bombard a 4 •off Si(111) substrate in order to grow nanosized SiC dots at temperatures of 800-950 • C. Kametani [9] reported that the CVD ferrocene (Fe(C 5 H 5 ) 2 ) precursor was used to form SiC nanodots on Si(111) substrates by deposition at 600 • C followed by annealing at 600-800 • C. Flores et al [10] reported that Si(111) substrates with high C content were annealed at 660-810 • C to form SiC nanodots by segregation of carbon atoms from the bulk to the surface and reacted with Si to form SiC nanodots. In this paper, a novel approach to the synthesis of SiC nanoparticles on Si(100) wafers using an ultra-high-vacuum ion beam sputtering process followed by vacuum thermal annealing is reported.…”

Section: Introductionmentioning

confidence: 99%

Thermally induced formation of SiC nanoparticles from Si/C/Si multilayers deposited by ultra-high-vacuum ion beam sputtering

Chung¹,

Wu²

2006

Nanotechnology

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A novel approach for the formation of SiC nanoparticles (np-SiC) is reported. Deposition of Si/C/Si multilayers on Si(100) wafers by ultra-high-vacuum ion beam sputtering was followed by thermal annealing in vacuum for conversion into SiC nanoparticles. The annealing temperature significantly affected the size, density, and distribution of np-SiC. No nanoparticles were formed for multilayers annealed at 500 °C, while a few particles started to appear when the annealing temperature was increased to 700 °C. At an annealing temperature of 900 °C, many small SiC nanoparticles, of several tens of nanometres, surrounding larger submicron ones appeared with a particle density approximately 16 times higher than that observed at 700 °C. The higher the annealing temperature was, the larger the nanoparticle size, and the higher the density. The higher superheating at 900 °C increased the amount of stable nuclei, and resulted in a higher particle density compared to that at 700 °C. These particles grew larger at 900 °C to reduce the total surface energy of smaller particles due to the higher atomic mobility and growth rate. The increased free energy of stacking defects during particle growth will limit the size of large particles, leaving many smaller particles surrounding the large ones. A mechanism for the np-SiC formation is proposed in this paper.

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“…On the contrary, the higher deposition temperature (normally above750 °C) makes the landing carbon atoms energetically reacted with Si atoms on the surface and aggregated into large islands. The step edges are etched into irregular kinks . In our case, the deposition temperature is selected at about 600 °C.…”

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confidence: 99%

Assembly of Metallic Carbon Nanodots Aligned on a Vicinal Si(111)-7×7 Surface

et al. 2007

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Self-assembly of nanostructures with ordered arrangement on the step edges of a vicinal silicon surface has attracted substantial attention 1 and has been demonstrated in several systems, including Au atomic chains, Si atomic wires, periodic clusters, and SiC nanodots arrays. 2 These nanostructures grown using templates of sharp silicon step edges with uniform and controllable size are of potential applications in single-electron transistors, ultra-highdensity storage media, and bionanosensors. 3 In this Communication, we report that pure carbon deposited on a vicinal Si(111)-7×7 surface can assemble into a nanodot array along the sharp step edges with a size ranging from 5 to 30 nm. These nanodots perform a metallic transport on the p-type silicon.We carried out the assembly of carbon nanodots on vicinal silicon surfaces in an ultra-high-vacuum (UHV) apparatus with a base pressure of 10 -10 Torr. The p-type Si(111) substrates with resistivity of ∼0.01 Ωcm were used for deposition. The vicinal silicon (111) surface with sharp and parallel step edges was first reported by the Himpsel group. 4 We prepared the substrate by flashing at 1260°C for 10 s. We quenched it to 800°C in a few seconds to skip the coexisting phase between the 1 × 1 and the 7 × 7 reconstructions around 860°C. Then, the substrate was annealed at 800°C for 10 h with dc current in the direction parallel to the step edge to produce the straight-step array. A pure graphite rod (purity 99.99%) was used as the source of electron-beam evaporation, the deposition rate was controlled at ∼0.04 monolayer (ML)/min (1 ML ) 7.8 × 10 14 atoms/cm 2 ), and the substrate temperature was held around 600°C. The original silicon(111) reconstruction surface and carbon deposited surfaces were observed by Omicron scanning tunneling microscopy (STM) in the UHV apparatus at constant current mode at sample biases between -2 and 2 V and a tunneling current of 0.20-0.25 nA. All STM images were recorded at room temperature. The carbon deposited sample was examined by ultraviolet (UV) micro-Raman to identify bonding structures of carbon nanodots on the silicon surface. Raman spectra were taken by a Renishaw microprobe RM1000B with a 514-nm Ar ion laser at a laser power of 1-2 mW, with light polarized linearly along the step-edge direction. Figure 1a shows the STM image of the Si(111) surface after carbon deposition for 1 h around 600°C. It can be seen that the carbon atoms accumulate and aggregate into nanodots aligned on the sharp and parallel step edges of the vicinal silicon surface. The nanodots have a size ranging from 5 to 30 nm and a height ranging from 0.8 to 3.5 nm and the density is ∼200 µm -2 . The formation of the three-dimensional (3D) nanodots is stimulated by the mismatch between C and Si lattice constants (Volmer-Weber growth mode). 5 From the 3D topographic images shown in Figure 1c, we see that the nanodots exhibit a pyramid-like morphology and clear facets, which means that the nanodots are crystallized. With the increase of deposition time, for example 9...

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Thermal effects in the size distribution of SiC nanodots on Si(111)

Cited by 14 publications

References 23 publications

Ordered array of self-assembled SiC nanocrystals fabricated by selective oxide desorption and nanosphere lithography

Ordered array of self-assembled SiC nanocrystals fabricated by selective oxide desorption and nanosphere lithography

Thermally induced formation of SiC nanoparticles from Si/C/Si multilayers deposited by ultra-high-vacuum ion beam sputtering

Assembly of Metallic Carbon Nanodots Aligned on a Vicinal Si(111)-7×7 Surface

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