KR20090085430A - Monocrystalline Silicon Nanoribbons and Manufacturing Method Thereof - Google Patents

Abstract

The present invention relates to a single crystal Si nanoribbon and a method for manufacturing the same. More specifically, a silicon substrate (Si substrate) free of impurities is formed of a titanium (Ti) layer and platinum (Pt) having a predetermined thickness. ) Layer is successively coated and produced by transporting silicon-tetra chloride (SiCl4) as a starting material by vapor-liquid-solid mechanism (VLS mechanism). And grown single crystal silicon nanoribbons and a method of manufacturing the same. At this time, the use of platinum (Pt) and the titanium layer as a catalyst will be a key element of the present invention. Thus, reliability, and reproducibility is excellent and can generate a 1-dimensional silicon nanostructure of functionality and, in particular, high-crystallinity (high crystallinity), the semiconductive (semiconductivity), and very distinct surface area (high specific surface Single crystal silicon nanoribbons having unique properties such as area ) can be prepared. Such single crystal silicon nanoribbons have advantages that can be applied to sensors, optoelectronic devices, electronic devices, and electrochemical nanodevices. In other words, the compatibility of the nanoribbons with CMOS makes it possible to apply the nanoribbons to devices that can be applied to existing silicon-related manufacturing processes.

Description

Single Crystal Si nanoribbons and the manufacturing method of the same

The present invention relates to a single crystal Si nanoribbon and a method for manufacturing the same. More specifically, a silicon substrate (silicon substrate) free of impurities is formed of a titanium (Ti) layer and platinum (Pt) having a predetermined thickness. ) Layer is continuously coated and produced by transporting silicon tetrachloride (SiCl4) as a starting material by vapor-liquid-solid mechanism (VLS mechanism). And grown single crystal silicon nanoribbons and a method of manufacturing the same.

Nano materials have been the subject of much research due to their electrical, magnetic, optical and mechanical properties, which are different from bulk materials. The nanometer size is arithmetically reduced to micrometer (10 ^-6 m) to 1/1000, but the smaller the material, the more diverse and unusual physical and chemical properties in a given space. It is characteristic. That is, most of the materials retain the physical properties that appear in most bulk forms at the micrometer size, but when scaled down to nanometer sizes, they typically exhibit very different physical properties from the bulk form.

In particular, nanotubes, nanowires, and nanoribbons, which are one-dimensional nanomaterials, have been intensively researched as fields having great potential in the development of new physical properties and nano-sized devices, which are clearly contrasted with bulk materials.

These one-dimensional nanomaterials and nanoribbons can provide new properties due to the morphological elements having a nanometer-sized rectangular structure in the development of optical, mechanical and electrical nanodevices related thereto.

The crystal structure, chemical composition, and microstructure of the nanoribbons have a great influence on the final physical properties of the manufactured nanoribbons.

In order to realize such optimized properties and at the same time produce nanoribbons of desired size, waveguide, lasing action, nonlinearity of photons in 3-5 (III-V) group and oxide semiconductor nanoribbons Although new physical properties such as nonlinear polarization and high mechanical flexibility have been found, the production and growth technology of single crystal silicon nanoribbons has not been developed yet.

In particular, in order for the single crystal silicon nanoribbons to be compatible with CMOS and to be applicable to various optical devices and electronic devices, the single crystal silicon nanoribbons should be manufactured to have a width and thickness of a predetermined level or more. There was a problem that the production of nanoribbon was not easy.

The present invention has been made to solve the above problems, and an object of the present invention is to implement a one-dimensional single crystal silicon nanostructure excellent in reliability and reproducibility.

In addition, another object of the present invention is to implement a method for producing single crystal silicon nanoribbons having high crystallinity, semiconductivity, and high specific surface area.

In addition, another object of the present invention is to implement a method for manufacturing single crystal silicon nanoribbons compatible with CMOS, which is applicable to sensors, electronic devices, photoelectric devices, electrochemical devices, and the like.

In addition, another object of the present invention is to implement a method for producing a single crystal silicon nanoribbon having a thicker thickness and a wider width than a nanostructure implemented by a conventional method, and a nanoribbon prepared by the method.

The present invention to achieve the above object, forming a titanium layer on a silicon substrate; Forming a platinum layer over the titanium layer; And forming a single crystal silicon nanoribbon on the substrate by adding a silicon compound to the silicon substrate having the titanium layer and the platinum layer formed thereon.

Here, the forming of the single crystal silicon nanoribbons is preferably a step formed by first adding the silicon compound to form single crystal silicon nanowires and then further extending the reaction time.

In addition, the step of forming the single crystal silicon nanoribbons, it is preferable that the silicon is grown in a saw blade shape from the single crystal silicon nanowires are formed.

In addition, the single crystal silicon nanowires are formed by growing in the [110] direction, the nanoribbon is preferably formed by growing in the [1-12] direction from the nanowires.

In addition, the single crystal silicon nanoribbon is preferably formed with a thickness of 5 to 50nm, and a width of 0.1 to 2㎛.

In addition, the platinum layer is 1 to 10nm, the titanium layer is preferably 10 to 30nm thickness.

In addition, the silicon compound is preferably silicon tetrachloride (SiCl 4).

In addition, the present invention provides a single crystal silicon nanoribbons having a thickness of 5 to 50nm, and a width of 0.1 to 2㎛ in order to achieve the above object.

The present invention has the following effects and advantages.

The single crystal silicon nanoribbons produced by the present invention are excellent in reliability and reproducibility.

In addition, the single crystal silicon nanoribbons produced by the present invention have high crystallinity, semiconductivity and distinct surface area.

In addition, the single crystal silicon nanoribbons manufactured by the present invention are applicable to sensors, electronic devices, photoelectric devices, electrochemical devices, and the like, and are compatible with CMOS, and thus have an effect of replacing CMOS.

In addition, since the single crystal silicon nanoribbon prepared by the present invention has a thicker thickness and a wider width than the nanostructure implemented by the conventional method, the application has a wide range of effects.

Hereinafter, the present invention will be described in more detail based on the preferred embodiments thereof.

Single crystal silicon (Si) nanoribbons are synthesized and formed on a silicon substrate using a vapor-liquid-solid (VLS) apparatus, using platinum (Pt) as a catalyst. Such nanoribbons comprise a silicon compound, preferably silicon-tetra chloride (SiCl 4), having a thickness of 10-30 nm (preferably 20 nm) of titanium and a thickness of 1-10 nm (preferably 5 nm) of platinum. The (Pt) layer is grown by mass transfer on a successively coated silicon substrate.

1 illustrates a microstructure observed using a scanning electron microscope (SEM) of a single crystal silicon nanoribbon grown on a substrate according to an embodiment of the present invention, Figures 2 and 3 is an embodiment of the present invention The microstructures observed by SEM and transmission electron microscopy (TEM) of single crystal silicon nanoribbons according to the examples are shown. The nanoribbons were characterized by a thickness of 10-30 nm, a width of less than 2 μm and a length of several hundred μm.

4 is a microstructure observed using a high-resolution transmission electron microscopy (HRTEM) of a single crystal silicon nanoribbon according to an embodiment of the present invention, as shown as a defect (defect) or secondary phase Single crystals were observed in which no secondary phase was produced. Here, according to the selected area electron diffraction (SAED) analysis, it can be seen that the nanoribbons are single crystals of diamond structure.

5 is an energy dispersive X-ray spectroscopy (EDX) analysis result of single crystal silicon nanoribbons according to an embodiment of the present invention, as shown, as shown, single crystal silicon according to the present invention The nanoribbon was found to be free of impurities, including platinum (Pt) and titanium (Ti).

The production mechanism of the single crystal silicon nanoribbons was investigated by using the growth time as a variable, which is shown as a continuous progress step of the single crystal silicon nanoribbons according to an embodiment of the present invention according to the treatment time of FIG. 6.

First, one-dimensional silicon nanowires are grown in the [110] direction. Thereafter, as the reaction time increases, the end of the saw-like shape begins to grow in the [1-12] direction along the base line of the nanowire.

As the reaction time continues to increase, the silicon triangular vertices of the sawtooth-grown body growing from the nanowires begin to be filled, and after all the interspaces are filled, a nanoribbon as shown in FIG. 6 is generated. .

FIG. 7 is an analysis photograph of a single crystal silicon nanoribbon according to an embodiment of the present invention by transmission electron microscopy for an interface between a nanowire, an end portion of a saw blade, and an interface between the nanowire and an end portion of the saw blade. Here, the SAED pattern recorded along the axis of the [-111] region shows that the nanowire portion in the ribbon grew along the [110] direction and the saw blade-shaped end portion grew along the [1-12] direction.

The growth mechanism of silicon nanoribbons is based on the well-known VLS mechanism, and all processes are similar to ZnO broadband nanosheets, especially the “1D branching and subsequent 2D interpace filling” process.

Here, it should be noted that the platinum (Pt) catalyst and the titanium (Ti) interlayer are the most important factors for the growth of nanoribbons.

This process can be summarized by considering these parameters, which can also be seen by FIG. 8. First, nanowires are grown by the VLS apparatus through platinum catalysts.

Quantitative analysis showed that platinum used as catalyst was not detected at the end of the saw-like shape, so that the saw-shaped end produced from the base of the nanowire did not contribute to the VLS mechanism, but rather limited diffusion. It contributes to the vapor-solid mechanism, which proceeds under limited diffusion and supersaturated vapor environment.

Under this atmosphere, morphological instability can be caused by the VS mechanism without the catalyst being used, and at this saw blade end, a typical fern-like ice crystal is observed.

An important point at this stage is that silicon nanowires are c.a. Growing in the [110] direction with a diameter of 20 nm, the VS instrument induces the sawtooth-shaped end to epitaxially grow in the [1-12] direction from the base side of the nanowire.

As a comparative example of an embodiment of the present invention, a gold (Au) catalyst or a platinum (Pt) catalyst without a titanium (Ti) layer was used. As a result, c.a. It was found that there was no saw blade end portion growing to have a diameter of 50 nm or more.

In other words, nanoribbons of a predetermined size or more as in the present invention can be said to be possible only in the presence of a titanium layer and a platinum layer.

Compared with existing gold (Au) catalyst systems for growing silicon nanowires, the platinum used as catalyst in the present invention has a higher eutectic point with silicon as well as surface energy. Therefore, droplets of smaller size may be formed in the early stages of the VLS apparatus than in the gold catalyst system. The higher platinum-titanium eutectic point (1310 ° C.) compared to the platinum-silicon eutectic point (830 ° C.) prevents silicon from dissolving into the platinum catalyst from the silicon substrate in the early stages of the VLS instrument, and thus the smaller size. Contributes to the formation of droplets.

Since the diameter of the nanowires in the VLS apparatus depends on the droplet size of the liquid catalyst, the silicon nanowires grown with the help of the platinum catalyst and the titanium layer have a diameter of 20 nm or less, which is shown in FIG. 6. In this diameter region, silicon nanowires tend to grow in the [110] direction because silicon surface energy called edge tension interacts as a liquid-solid interface energy.

Saw blade growth is a result of diffusion limited crystal growth in terms of nanowires in a supersaturated gas atmosphere, as is typically observed in Mullin-Sekerka instability.

The surface energy of the nanowires is determined by the growth direction and the diameter, and the nanowires according to the present invention may have surface energy that enables the growth of the saw blade-shaped end portion under the supersaturation process atmosphere.

Planar filling of the side branch interspace is achieved by selective agglomeration of the gas phase in the concave corners between the branches, the upper corners having lower chemical potentials (i.e. equilibrium pressure) than at the convex or flat sections. This can be explained from the Gibbs-Thomson relationship.

In short, the growth of nanoribbons can be explained by three continuous mechanisms, which are as follows.

(1) Growth in the [110] direction from the base of the nanowires (available through the VLS process using a platinum catalyst and a titanium buffer layer)

(2) Saw blade-shaped end growth (possible by VS process under supersaturated atmosphere)

(3) planar filling (optional condensation)

FIG. 8 is a diagram illustrating the production of a single crystal silicon nanoribbon prepared according to an embodiment of the present invention, the embodiment of the present invention as described above is completed through the process as shown.

The growth model of the silicon nanoribbons as in the present invention allows the construction of new areas of one-dimensional silicon nanostructures that are characterized, reliable and excellent in reproducibility.

The monocrystalline nanoribbons prepared as in the present invention have properties such as unique physical properties, such as high crystallinity, semiconductivity and very pronounced surface area, and from this, sensors, optoelectronic devices, electronic devices and electrochemical nanodevices, etc. Applicable.

The compatibility of the single crystal silicon nanoribbons with CMOS may enable the nanoribbons to be applied to devices using existing silicon manufacturing processes.

1 is a microstructure photograph of a single crystal silicon nanoribbon grown on a substrate by using a scanning electron microscope (SEM, Scanning electron microscopy) according to an embodiment of the present invention.

Figure 2 is a microstructure photograph observed using the SEM of the single crystal silicon nanoribbon according to an embodiment of the present invention.

FIG. 3 is a microstructure photograph of a single crystal silicon nanoribbon using a transmission electron microscopy (TEM). FIG.

4 is a microstructure photograph of a single crystal silicon nanoribbon according to an embodiment of the present invention using high-resolution transmission electron microscopy (HRTEM).

5 is a view showing an energy dispersive X-ray spectroscopy (EDX) analysis results of single crystal silicon nanoribbons according to an embodiment of the present invention.

Figure 6 relates to the production mechanism of the single crystal silicon nanoribbons of the present invention a photo showing the continuous progress of the nanoribbons with reaction time.

Fig. 7 is a photograph of analysis by transmission electron microscopy for the interface between the nanowires, the saw blade-shaped end portions, and the nanowires and the saw blade-shaped ends of the single crystal silicon nanoribbons according to an embodiment of the present invention.

8 is a diagram illustrating a production process of a single crystal silicon nanoribbon according to an embodiment of the present invention.

Claims (8)

Forming a titanium layer on the silicon substrate; Forming a platinum layer over the titanium layer; And Adding a silicon compound to the silicon substrate on which the titanium layer and the platinum layer are formed to form single crystal silicon nanoribbons on the substrate; Method of producing a single crystal silicon nanoribbon characterized in that it comprises a. The method of claim 1, Forming the single crystal silicon nanoribbons, First, the silicon compound is added to form a single crystal silicon nanowire, and then the reaction time is formed by extending the reaction time. The method of claim 2, Forming the single crystal silicon nanoribbons, Method for producing a single crystal silicon nanoribbon, characterized in that the step of growing silicon is formed in the saw blade shape from the single crystal silicon nanowires. The method of claim 2, The single crystal silicon nanowires are formed by growing in the [110] direction, wherein the nanoribbon is a method of producing a single crystal silicon nanoribbons, characterized in that formed by growing in the [1-12] direction from the nanowires. The method according to any one of claims 1 to 4, The nanoribbons are 5 to 50nm in thickness, 0.1 to 2㎛ method for producing a single crystal silicon nanoribbon, characterized in that formed. The method according to any one of claims 1 to 4, The platinum layer is a method of producing a single crystal silicon nanoribbon, characterized in that the thickness of 1 to 10nm, the titanium layer is 10 to 30nm. The method according to any one of claims 1 to 4, The silicon compound is silicon tetrachloride (SiCl4) method for producing a single crystal silicon nanoribbon characterized in that. Prepared by the method of any one of claims 1 to 4, A single crystal silicon nanoribbon having a thickness of 5 to 50 nm and a width of 0.1 to 2 μm.

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