阅读说明：本技术 制造石墨烯结构和装置的方法 (Methods of fabricating graphene structures and devices ) 是由 西蒙·托马斯 伊沃尔·吉尼 于 2019-01-10 设计创作，主要内容包括：本发明提供了用于生产具有1至100个石墨烯层的石墨烯层结构的方法,所述方法包括：将热阻等于或大于蓝宝石的热阻的基底设置在反应室中的加热的衬托器上,所述室具有复数个冷却的入口,所述复数个冷却的入口布置成使得在使用时入口跨基底分布并且相对基底具有恒定的间隔,通过入口供应包含前体化合物的流并使其进入反应室,从而使前体化合物分解并在基底上形成石墨烯,其中入口被冷却至低于100℃,优选50℃至60℃,并且衬托器被加热至超过前体的分解温度至少50℃的温度,使用激光从基底选择性地烧蚀石墨烯,其中激光的波长超过600nm并且功率小于50瓦。(The present invention provides a method for producing a graphene layer structure having 1 to 100 graphene layers, the method comprising: disposing a substrate having a thermal resistance equal to or greater than that of sapphire on a heated susceptor in a reaction chamber, the chamber having a plurality of cooled inlets arranged such that, in use, the inlets are distributed across the substrate and at a constant spacing relative to the substrate, supplying a stream comprising a precursor compound through the inlets and into the reaction chamber to decompose the precursor compound and form graphene on the substrate, wherein the inlets are cooled to less than 100 ℃, preferably 50 ℃ to 60 ℃, and the susceptor is heated to a temperature at least 50 ℃ above the decomposition temperature of the precursor, selectively ablating graphene from the substrate using a laser, wherein the wavelength of the laser is in excess of 600nm and the power is less than 50 watts.)

1. A method for producing a graphene layer structure having from 1 to 100 graphene layers, the method comprising:

providing a substrate having a thermal resistance equal to or greater than that of sapphire on a heated susceptor located in a reaction chamber, the chamber having a plurality of cooled inlets arranged such that, in use, the inlets are distributed across the substrate and have a constant spacing relative to the substrate,

supplying a flow containing a precursor compound through the inlet and into the reaction chamber, thereby decomposing the precursor compound and forming graphene on the substrate,

wherein the inlet is cooled to less than 100 ℃, preferably 50 ℃ to 60 ℃, and the susceptor is heated to a temperature at least 50 ℃ above the decomposition temperature of the precursor,

selectively ablating graphene from the substrate using a laser,

wherein the laser has a wavelength in excess of 600nm and a power of less than 50 watts.

2. The method according to any one of the preceding claims, wherein the substrate comprises sapphire or silicon carbide, preferably sapphire.

3. The method of claim 1 or claim 2, wherein the laser:

(a) having a wavelength of 700nm to 1500 nm; and/or

(b) With a power of 1 watt to 20 watts.

4. The method of claim 1 or claim 2, wherein the laser:

(a) having a wavelength of at least 8 μm, preferably 9 μm to 15 μm, and most preferably 9.4 μm to 10.6 μm; and/or

(b) With a power from 5 watts to less than 50 watts.

5. The method according to any of the preceding claims, wherein the precursor compound is a hydrocarbon, preferably a hydrocarbon that is liquid at room temperature, most preferably C₅To C₁₀An alkane.

6. The method of claim 5, wherein the precursor compound is hexane.

7. The method of any of the preceding claims, wherein the diameter of the substrate is at least 6 inches.

8. The method of any preceding claim, wherein the step of selectively ablating graphene from the substrate using a laser further comprises etching away at least a portion of the substrate, preferably to a depth of 1nm to 300 nm.

9. The method of any one of the preceding claims, further comprising removing the graphene layer structure from the substrate.

10. A method according to any preceding claim for producing a hall sensor, the method comprising:

selectively ablating graphene using the laser, thereby defining a hall sensor portion of the graphene on the substrate.

11. The method of claim 10, for providing a plurality of hall sensor portions on the substrate.

12. A method according to claim 10 or claim 11 for producing a hall sensor device precursor, the method comprising:

selectively ablating graphene using the laser, thereby defining hall sensor portions of the graphene on the substrate, and associated graphene wiring circuitry for connection with electronic components to complete the hall sensor device.

13. The method of any preceding claim, further comprising applying a contact to a surface of the graphene layer structure.

14. A method according to any one of claims 1 to 9 for producing a graphene layer structure for producing a filter, the method comprising:

selectively ablating a plurality of holes distributed across the graphene surface using the laser; and

separating the graphene from the substrate.

15. The method of claim 14, wherein the graphene is separated from the substrate after the step of selectively ablating a plurality of holes distributed across the graphene surface using the laser.

Examples

The invention will now be further described with reference to the following non-limiting examples.

An exemplary process using the above-described apparatus is described below, which successfully produces a graphene layer structure having 1 to 40, preferably 1 to 10 graphene layers. In all examples, a tightly coupled vertical reactor with a diameter of 250mm and six target substrates of 2"(50mm) were used. For alternate sized reactors and/or different target substrate areas, the precursor and gas flow rates can be scaled by theoretical calculations and/or empirical experiments to achieve the same results.

Using the method of the present invention, such patterned graphene can be produced: which has greatly improved properties over known methods, such as grain size greater than 20 μm, coverage of 6 inch diameter substrates with 98% coverage, layer uniformity>95% of the substrate, sheet resistivity less than 450Q/sq, and electron mobility greater than 2435cm²Vs. Recent tests of graphene layers produced using the method of the invention have demonstrated testing under standard conditions of temperature and pressureElectron mobility over the entire layer>8000cm²Vs. The method is capable of producing graphene layers across 6 inch (15cm) substrates that have undetectable discontinuities as measured to the micron scale by standard raman and AFM mapping (AFM mapping) techniques. The method also shows that it is possible to produce uniform graphene monolayers across the substrate and stacked uniform graphene layers without forming additional layer fragments, individual carbon atoms or groups of carbon atoms on the top or uppermost uniform monolayer.

The following description details how to fabricate one graphene monolayer on a sapphire substrate using a Metal Organic Chemical Vapor Deposition (MOCVD) method, thereby achieving a high quality, high mobility material suitable for electronic devices.

I. Sapphire wafers were loaded into the MOCVD reactor chamber.

Closing the reactor, which results in the gas injector being located 10mm to 11mm above the substrate surface.

Reactor compartment pump purge cycle to remove any existing ambient.

A stream of 10slm of hydrogen was introduced to the reactor and kept constant.

V. reduce the reactor pressure to 50 mbar.

Heating the reactor temperature (i.e., susceptor) and through the bonded wafer to 1050 deg.C

After the set point was reached, the temperature was allowed to stabilize for 3 minutes.

Hexane was introduced into the reactor chamber at a flow rate of 0.1slm for a period of 2 minutes via a gas stream obtained from a liquid source. This allows the formation of graphene "nucleation" structures on the substrate surface.

IX. Hexane flow was turned off.

X. raise the wafer temperature to 1350 ℃.

After the set point was reached, the temperature was allowed to stabilize for 3 minutes.

Hexane was reintroduced into the reactor chamber again via the gas stream obtained from the liquid source, this time at a flow rate of 0.2slm for 8 minutes.

XIII, the hexane flow to the reactor chamber is closed

The reactor was cooled to room temperature over 15 minutes with hydrogen still flowing

XV. use nitrogen to raise the reactor chamber back to atmospheric pressure

The wafer can now be unloaded.

By varying some of the variables described above, such as gas flow, hexane flow, substrate temperature, the process described above can be varied to produce graphene with slightly varying properties (e.g., carrier concentration and electron mobility).

The sapphire wafer had a thermal conductivity (reciprocal of thermal resistance) of 30.3W/mK at 298K orthogonal to the C-axis, a thermal conductivity of 32.5W/mK parallel to the C-axis, and 27.2W/mK at 60 ℃. An alternative substrate may be used at 298K, provided that it has a lower or equal thermal conductivity (i.e., higher thermal resistance).

The following is a description of how to fabricate a hall effect sensor using the wafer level graphene material described above. The following fabrication process uses graphene on a sapphire substrate produced using the above method.

I. Placing a custom designed mask on the graphene wafer, leaving only the areas where electrical contacts need to be exposed

Electrical contacts comprising 5nm chromium and 70nm gold were deposited onto the graphene surface through a mask using standard metal deposition techniques (e.g. electron beam deposition).

Removing the wafer from the metal deposition system and removing the mask from the wafer.

Placing the wafer into a laser etching system. The power is about 8W, but here there is a rather wide window depending on the thermal insulation properties of the substrate.

V. laser is aligned to the graphene wafer and set at a power and wavelength suitable for ablating graphene from the wafer surface.

Control the laser so that the pattern is ablated into the graphene material. These patterns form the shape of the desired device. The vaporization (vaporization) of the graphene is controlled such that a pattern is formed around the deposited electrical contacts without overlap. With good control, this allows multiple graphene hall effect sensors to be formed on a single wafer

Removing the wafer from the laser patterning system to implement a plurality of graphene-based sensors on the sapphire substrate.

All percentages herein are by weight unless otherwise indicated.

The foregoing detailed description is provided by way of explanation and illustration, and is not intended to limit the scope of the appended claims. Many variations in the presently preferred embodiments shown herein will be apparent to one of ordinary skill in the art and still be within the scope of the appended claims and their equivalents.