Patent Application
20080187685
The present invention relates to preparing carbon nanotubes; more particularly, relates to using an external high frequency source and a perpendicularly-supplied gas material source for a cold-wall heating treatment under a non-vacuum environment to directly grow carbon nanotubes having a vertically-aligned arrangement on a surface of a catalyst material.
As early as 1991, Mr. Sumio Lijima in NEC Co., Japan found a carbon nanotube formed in an arc discharging device. Because the carbon nanotube has good electronical and mechanical characteristics, it can be applied to electronical devices, computing devices and field emitting devices; or sensors, electrodes, high-strength composite materials, etc.
In the early days, carbon nanotubes are fabricated through laser ablation or arc discharging. On being fabricated through the laser ablation, it is hard to be productive. Through arc discharging, carbon nanotubes are productive yet with less purity.
In recent years, carbon nanotubes are fabricated mainly through plasma-enhanced chemical vapor deposition (PECVD) and hot-wall heating treatment. However, PECVD has to be operated under a vacuum environment; and the hot-wall heating treatment has a slow temperature change resulting in a longer time spent.
Hence, the prior arts do not fulfill users' requests on actual use.
The main purpose of the present invention is to use a perpendicularly-supplied gas material source and an external high frequency source for a cold-wall heating treatment under a non-vacuum environment to directly grow carbon nanotubes having a vertically-aligned arrangement on a surface of a catalyst material.
To achieve the above purpose, the present invention is a method of preparing vertically-aligned carbon nanotubes under atmospheric and cold-wall heating treatments and making the same, comprising steps of: (a) obtaining a silicon (Si) substrate; (b) by using an electron-beam gun (E-gun) evaporation system, coating a buffer layer and a catalyst layer; (c) deposing the Si substrate into a reaction furnace for atmospheric pressure chemical vapor deposition (APCVD) to grow carbon nanotubes with an external high frequency source and a perpendicularly-supplied gas material source for a cold-wall heating treatment; and (d) cooling down temperature to room temperature to finish growing carbon nanotubes, where the reaction furnace is operated under 1 atmosphere between 800 and 850 Celsius degrees (° C.); after a pre-treatment for 1 to 10 minutes (min), temperature is lowered to a temperature between 700 and 800° C.; the carbon nanotubes are grown for 0.1 to 10 min with a speed of several micrometers per minute (μm/min and a vertically aligned arrangement; and the temperature is fast ascended and descended to save time and power consumption. Accordingly, a novel method of preparing vertically-aligned carbon nanotubes under atmospheric and cold-wall heating treatments and making the same is obtained.
The present invention will be better understood from the following detailed description of the preferred embodiment according to the present invention, taken in con junction with the accompanying drawings, in which
The following description of the preferred embodiment is provided to understand the features and the structures of the present invention
Please refer to
(a) Obtaining a Si substrate 11: As shown in
(b) Processing an E-gun evaporation 12: As shown in
(c) Deposing into a reaction furnace of APCVD 13: As shown in
(d) Cooling down to room temperature 14: And, as shown in
To sum up, the present invention is a method of preparing vertically-aligned carbon nanotubes under atmospheric and cold-wall heating treatments and making the same, where an APCVD is used under a non-vacuum environment with an external high frequency source and a perpendicularly-supplied gas material source for a cold-wall heating treatment to directly grow carbon nanotubes on a surface of a catalyst material; the equipments used are simple; temperature is fast ascended and descended; less power is consumed; and carbon nanotubes are grown faster, purer and more productive.
The preferred embodiment herein disclosed is not intended to unnecessarily limit the scope of the invention. Therefore, simple modifications or variations belonging to the equivalent of the scope of the claims and the instructions disclosed herein for a patent are all within the scope of the present invention.
