Electronics device having two-dimensional (2D) material layer and method of manufacturing the electronic device by inkjet printing

An electronic device includes first and second electrodes that are spaced apart from each other and a 2D material layer. The 2D material layer connects the first and second electrodes. The 2D material layer includes a plurality of 2D nanomaterials. At least some of the 2D nanomaterials overlap one another.

RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2014-0194323, filed on Dec. 30, 2014, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

The present disclosure relates to electronic devices including two-dimensional (2D) material layers and/or methods of manufacturing the electronic devices by inkjet printing.

2. Description of Related Art

Graphene has a structure in which carbon atoms are connected to one another in a two-dimensional (2D) manner. Graphene may have an atomic-level thickness. Graphene has a higher electron mobility and a higher thermal conductivity than silicon (Si). Graphene is chemically stable. Graphene may have a large surface area. However, since graphene may have a band gap of 0 eV, a transistor including graphene as a channel material may have a low on/off current ratio. Accordingly, a high standby current may be generated in a transistor including graphene. Thus, the operation efficiency of a transistor device including graphene may be reduced. Methods of modifying graphene have been suggested in order to improve the operation efficiency of a transistor including graphene. However, although an on/off current ratio of a transistor including graphene may be increased by modifying graphene, modifying graphene may also reduce the on-current density or carrier mobility and an increase manufacturing costs for a transistor device.

SUMMARY

The present disclosure relates electronic devices including two-dimensional (2D) material layers and/or methods of manufacturing the electronic devices by using inkjet printing.

According to example embodiments, an electronic device includes a first electrode, a second electrode spaced apart from the first electrode, and a two-dimensional (2D) material layer that is connected to the first and second electrodes. The 2D material layer includes a plurality of 2D nanomaterials. At least some of the 2D nanomaterials overlap one another.

In example embodiments, the 2D nanomaterials may have semiconductor characteristics.

In example embodiments, the 2D material layer may further include a conductive material. The conductive material may include at least one of graphene, conductive particles, conductive nanotubes, and conductive nanowires.

In example embodiments, 2D material layer may further include a dopant. The 2D material layer be a channel layer of the electrode device. The electronic device may further include a gate insulating layer on the 2D material layer, and a gate electrode on the gate insulating layer.

In example embodiments, a Schottky junction may be formed between the 2D material layer and at least one of the first and second electrodes. A p-n junction may be formed between the plurality of 2D nanomaterials.

In example embodiments, each of the plurality of 2D nanomaterials may include at least one layer.

In example embodiments, each of the plurality of 2D nanomaterials may include at least one of a transition metal dichalcogenide (TMD), phosphorene (black phosphorus), germanane, and silicene.

According to example embodiments, a method of manufacturing an electronic device includes forming by inkjet printing a two-dimensional (2D) material layer on a substrate, the 2D material layer including a plurality of 2D nanomaterials that have semiconductor characteristics and at least some of the 2D nanomaterials overlap one another, and forming a first electrode and a second electrode that are connected to the 2D material layer.

In example embodiments, the forming the 2D material layer may include forming an ink pattern by ejecting ink onto the substrate, and drying the ink pattern. The ink may include a solvent and the 2D nanomaterials.

In example embodiments, a mixture ratio of the 2D nanomaterials to the solvent in the ink may range from about 1 μg/mL to about 100 mg/mL.

In example embodiments, the ink may further include a conductive material. The ink may further include a dopant. The 2D nanomaterials may be doped with impurities.

In example embodiments, the first and second electrodes may be formed by inkjet printing.

In example embodiments, the method may further include forming a gate insulating layer on the 2D material layer, and forming a gate electrode on the gate insulating layer. The gate insulating layer and the gate electrode may be formed by inkjet printing.

According to example embodiments a method of manufacturing an electronic device includes forming a two-dimensional (2D) material layer, forming a first electrode connected to a first part of the 2D material layer, and forming a second electrode connected to a second part of the 2D material layer. The 2D material layer includes a plurality of 2D nanomaterials that have semiconductor characteristics. At least some of the 2D nanomaterials overlap one another. The second electrode is spaced apart from the first electrode.

In example embodiments, the method may further include forming a gate electrode on a substrate and forming a gate insulating layer on the substrate. The forming the 2D material layer may include inkjet printing an ink pattern on the substrate and drying the ink pattern. The ink may include a solvent and the 2D nanomaterials. The forming the gate insulating layer may include one of (i) forming the gate insulating layer on top of the gate electrode and (ii) forming the gate insulating layer between the gate electrode and the substrate. The gate insulating layer may extend between the 2D material layer and the gate electrode.

In example embodiments, the 2D nanomaterials may include one of a transition metal dichalcogenide (TMD), phosphorene, germanane, and silicene.

In example embodiments, the forming the first electrode may include forming a Schottky junction between the 2D material layer and the first electrode at the first part of the 2D material layer.

In example embodiments, the 2D material layer may include one of a conductive material and a dopant on the 2D nanomaterials. The conductive material may include one of graphene, conductive particles, conductive nanotubes, and conductive nanowires.

DETAILED DESCRIPTION

FIG. 1is a plan view illustrating an electronic device100according to example embodiments.FIG. 2is a cross-sectional view taken along line II-II′ ofFIG. 1. The electronic device100illustrated inFIGS. 1 and 2is a transistor device having an under-gate structure.

Referring toFIGS. 1 and 2, the electronic device100may include a gate electrode120, a gate insulating layer130, a two-dimensional (2D) material layer140, and first and second electrodes151and152. The gate electrode120may be provided on a substrate110. The substrate110may be, for example, a semiconductor substrate (e.g., silicon substrate). However, example embodiments are not limited thereto, and the substrate110may be formed of any of various materials. Also, the substrate110may be formed of a flexible material such as a plastic substrate. An insulating layer (not shown) may be further provided on a top surface of the substrate110in order to insulate the substrate110from the gate electrode120. The insulating layer may include, for example, but is not limited to, silicon oxide or silicon nitride. When the substrate110includes an insulating material, the insulating layer may not be provided on the top surface of the substrate110.

The gate electrode120may include a conductive material. For example, the gate electrode120may include graphene, carbon nanotubes (CNTs), or a metal such as silver (Ag), gold (Au), platinum (Pt), or copper (Cu). However, example embodiments are not limited thereto, and the gate electrode120may include any of other various conductive materials. The gate insulating layer130is provided on the substrate110to cover the gate electrode120. The gate insulating layer130may include various insulating materials. For example, the gate insulating layer130may include, but is not limited to, silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, hafnium oxide, and/or insulating polymer. The gate insulating layer130may be formed by using inkjet printing as described below.

The 2D material layer140is provided on the gate insulating layer130. The 2D material layer140may function as a channel layer. The 2D material layer140is disposed to correspond to the gate electrode120.FIG. 3is an enlarged cross-sectional view illustrating the 2D material layer140ofFIG. 2. As shown inFIG. 3, the 2D material layer140may be formed so that at least some of a plurality of 2D nanomaterials141overlap one another. The 2D nanomaterials141are nano-sized materials having semiconductor characteristics and having a 2D crystal structure.

Each of the 2D nanomaterials141may include one layer or a plurality of layers. For example, each of the 2D nanomaterials141may include tens of layers (e.g., about 10 to about 90 layers). Each layer of each of the 2D nanomaterials141may have a thickness that is equal to or less than about several nanometers (nm). For example, each layer of each of the 2D nanomaterials141may have, but is not limited to, a thickness that is greater than 0 nm and equal to or less than about 2 nm. Each layer of each of the 2D nanomaterials141may have a size that ranges from about tens of nm to about hundreds of nm (e.g., about 10 nm to about 900 nm). Each of the 2D nanomaterials141may have any of various planar shapes such as a quadrangular shape or a pentagonal shape.

As such, the 2D material layer140may be formed so that some of the 2D nanomaterials141overlap one another. The 2D material layer140may be formed by using inkjet printing as described below. The 2D material layer140that is formed by using inkjet printing may have a thickness that ranges from about several nm (e.g., 3 nm) to about hundreds of nm (e.g., about 100 to about 900 nm) and a size that ranges from about hundreds of nm to (e.g., 100 nm or more) about hundreds of micrometers (μm) (e.g., about 900 μm). As such, when the 2D material layer140is formed by using inkjet printing, the 2D material layer140may be formed to have a large area.

The 2D material layer140including the 2D nanomaterials141having semiconductor characteristics has lower mobility than graphene but has a bandgap that is greater than 0 eV. Accordingly, when the 2D material layer140is used as a channel layer of the electronic device100that is a transistor device, an on/off current ratio may be increased to be equal to or greater than 100, thereby improving operation efficiency of the electronic device100.

The first and second electrodes151and152are provided on both sides of the 2D material layer140. The first and second electrodes151and152are provided on the gate insulating layer130to be electrically connected to the 2D material layer140. The first and second electrodes151and152may be respectively a source electrode and a drain electrode. Alternatively, the first and second electrodes151and152may be a drain electrode and a source electrode. The first and second electrodes151and152may include a conductive material, like the gate electrode120. For example, the first and second electrodes151and152may include graphene, CNTs, or a metal such as Ag, Au, Pt, or Cu. As described below, the first and second electrodes151and152and the gate electrode120may be formed by using inkjet printing.

Although a case where the 2D material layer140includes the 2D nanomaterials141has been described, the 2D material layer140may further include a material in addition to the 2D nanomaterials141.FIG. 4is a cross-sectional view illustrating a modification of the 2D material layer140ofFIG. 2. Referring toFIG. 4, a 2D material layer140′ includes the plurality of 2D nanomaterials141and a conductive material142. The 2D nanomaterials141are provided so that at least some of the 2D nanomaterials141overlap one another. The conductive material142may be attached to the 2D nanomaterials141and may increase electrical conductivity between the 2D nanomaterials141. Accordingly, an on-current of the electronic device100may be increased due to the conductive material142that is included in the 2D material layer140.

The conductive material142that is included in the 2D material layer140may include at least one among, for example, graphene, conductive particles, conductive nanotubes, and conductive nanowires. The conductive particles may include at least one selected from the group consisting of, for example, Ag, Au, Pt, Cu, and fullerene. The conductive nanotubes may include, for example, CNTs. The conductive nanowires may include, for example, Ag nanowires. However, example embodiments are not limited thereto.

A dopant may be further included in the 2D material layer140including the 2D nanomaterials141or the 2D material layer140′ including both the 2D nanomaterials141and the conductive material142. The dopant may allow specific electric charges to pass therethrough. Accordingly, an off-current of the electronic device100may be reduced due to the dopant that is included in the 2D material layer140. The dopant may be included in ink when the 2D material layer140is formed by using inkjet printing as described below. The 2D nanomaterials141that are included in the 2D material layer140may be previously doped with impurities. The dopant may include an alkali metal (e.g., K or Li), AuCl3, or a polymer such as polyethylenimine, HPtCl4, AuCl3, HAuCl4, silver trifluoromethanesulfonate (AgOTf), AgNO3, H2PdCl6, Pd(OAc)2, Cu(CN)2, but is not limited thereto.

As described above, since the 2D material layer140including the 2D nanomaterials141having semiconductor characteristics is used as a channel layer of the electronic device100, operation efficiency of the electronic device100may be improved. When the 2D material layer140is formed by using inkjet printing as described below, the electronic device100may be formed to have a large area.

A method of forming a 2D material layer by using inkjet printing will now be explained.FIGS. 5A through 5Dare cross-sectional views for explaining a method of forming a 2D material layer, according to example embodiments.

Referring toFIG. 5A, an inkjet printing apparatus200is provided on a substrate250. The inkjet printing apparatus200may include an ink chamber220in which ink230for forming a 2D material layer240(seeFIG. 5D) is filled and an inkjet head210that ejects the ink230onto the substrate250. The inkjet printing apparatus200may eject the ink230by using, for example, but not limited to, thermal inkjet printing or piezoelectric inkjet printing.

The ink230for forming the 2D material layer240may be prepared by mixing the 2D nanomaterials241with the solvent243. A mixture ratio of the 2D nanomaterials241to the solvent243may range from, but is not limited to, about 1 μg/mL to about 100 mg/mL. The 2D nanomaterials241are nano-sized materials having semiconductor characteristics and a 2D crystal structure. Each of the 2D nanomaterials241may include one layer or a plurality of layers. Each layer of each of the 2D nanomaterials241may have a thickness equal to or less than about several nm and may have a size that ranges from about tens of nm to about hundreds of nm.

Each of the 2D nanomaterials241may include a semiconductor material. For example, each of the 2D nanomaterials241may include at least one selected from the group consisting of, for example, TMD, phosphorene (black phosphorus), germanane, and silicene. TMD may include at least one selected from the group consisting of, for example, MoS2, MoSe2, MoTe2, WS2, WSe2, WTe2, TaS2, TaSe2, TiS2, TiSe2, HfS2, HfSe2, SnS2, SnSe2, GeS2, GeSe2, GaS2, GaSe2, Bi2S3, Bi2Se3, and Bi2Te3. The 2D nanomaterials241may include an undoped semiconductor material. Alternatively, the 2D nanomaterials241may be doped with desired (and/or alternatively predetermined) impurities. In this case, the ink230may be prepared by mixing the 2D nanomaterials241that are previously doped with impurities with the solvent243.

A conductive material (not shown) may be further included in the ink230for forming the 2D material layer240. The conductive material may include at least one among, for example, graphene, conductive particles, conductive nanotubes, and conductive nanowires. The conductive particles may include at least one selected from the group consisting of, for example, Ag, Au, Pt, Cu, and fullerene. The conductive nanotubes may include, for example, CNTs. The conductive nanowires may include, for example, Ag nanowires. However, example embodiments are not limited thereto.

A dopant may be further included in the ink230for forming the 2D material layer240. That is, when the 2D nanomaterials241include an undoped semiconductor material, the dopant may be further mixed with the solvent243.

Referring toFIG. 5B, the ink230is ejected onto a desired (and/or alternatively predetermined) position of the substrate250by using the inkjet printing apparatus200. In this process, the inkjet head210may move in a desired (and/or alternatively predetermined) direction, and the ink230may be ejected as droplets211from the inkjet head210to form an ink pattern230′ on the substrate250. Referring toFIG. 5C, when inkjet printing ends, the ink pattern230′ including the 2D nanomaterials241and the solvent243may be formed in a desired (and/or alternatively predetermined) shape on the substrate250.

Referring toFIG. 5D, when the ink pattern230′ is dried to remove the solvent243, the 2D material layer240including the 2D nanomaterials241may be formed on the substrate250. The ink pattern230′ may be dried by using natural drying or by applying heat. As such, the 2D material layer240may be formed by using inkjet printing so that at least some of the 2D nanomaterials241overlap one another. The 2D material layer240may have a thickness that ranges from about several nm to about hundreds of nm and a size that ranges from about hundreds of nm to hundreds of μm. However, example embodiments are not limited thereto.

As described above, a dopant may be further included in the ink230for forming the 2D material layer240or the 2D nanomaterials241that are previously doped with desired (and/or alternatively predetermined) impurities may be included in the ink230. In this case, the 2D material layer240that is formed by using inkjet printing may include a semiconductor material having a desired (and/or alternatively predetermined) conductivity type. For example, the 2D material layer240may include a p-type semiconductor material or an n-type semiconductor material.

Also, as described above, a conductive material may be further included in the ink230for forming the 2D material layer240. The conductive material may include at least one among, for example, graphene, conductive particles, conductive nanotubes, and conductive nanowires. In this case, the conductive material in the 2D material layer240that is formed by using inkjet printing may increase electrical conductivity between the 2D nanomaterials241.

A method of manufacturing an electronic device including a 2D material layer will now be explained.

FIGS. 6A through 6Dare cross-sectional views for explaining a method of manufacturing an electronic device, according to example embodiments. An electronic device that is manufactured by using the method ofFIGS. 6A through 6Dmay be the electronic device100, which is a transistor device, ofFIGS. 1 and 2.

Referring toFIG. 6A, a substrate310is prepared, and then a gate electrode320is formed on the substrate310. The substrate310may be a semiconductor substrate. For example, the substrate310may be a silicon substrate. However, example embodiments are not limited thereto, and the substrate310may be a substrate formed of any of various materials. Also, the substrate310may be a substrate formed of a flexible material such as a plastic substrate. An insulating layer (not shown) may be further provided on a top surface of the substrate310in order to insulate the substrate310from the gate electrode320. The insulating layer may include, for example, but is not limited to, silicon oxide or silicon nitride. When the substrate310includes an insulating material, the insulating layer may not be provided on the top surface of the substrate310.

The gate electrode320is formed on the top surface of the substrate310. The gate electrode320may be formed by using inkjet printing. In this case, the gate electrode320may be formed by printing ink including a conductive material on the top surface of the substrate310by using an inkjet printing apparatus and then drying the ink. The conductive material that is included in the ink may include at least one selected from the group consisting of, for example, but not limited to, graphene, Ag particles, Au particles, Pt particles, Cu particles, CNTs, and Ag nanowires. The gate electrode320may be formed by using another deposition method, instead of inkjet printing.

Referring toFIG. 6B, a gate insulating layer330is formed on the substrate310to cover the gate electrode320. The gate insulating layer330may include a high-k dielectric material. For example, the gate insulating layer330may include, but is not limited to, silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, hafnium oxide, and/or insulating polymer. The gate insulating layer330may be formed by using inkjet printing. In this case, the gate insulating layer330may be formed by printing ink including a desired (and/or alternatively predetermined) insulating material on the substrate310by using an inkjet printing apparatus to cover the gate electrode320and then drying the ink. The gate insulating layer330may be formed by using another deposition method, instead of inkjet printing.

Referring toFIG. 6C, a 2D material layer340is formed on the gate insulating layer330. The 2D material layer340may be disposed to correspond to the gate electrode320. The 2D material layer340that functions as a channel layer may be formed so that 3D nanomaterials341having semiconductor characteristics overlap one another.

The 2D material layer340may be formed by using inkjet printing as described above. In this case, the 2D material layer340may be formed by printing ink in which the 2D nanomaterials341are mixed with a solvent on a top surface of the gate insulating layer330by using an inkjet printing apparatus and then drying the ink. The solvent may include at least one selected from the group consisting of, for example, but not limited to, water, acetone, methanol, ethanol, isopropanol, cyclohexanone, cyclohexane, chlorobenzene, chloroform, formamide, N-methyl formamide, N-methyl pyrrolidinone, N-vinyl pyrrolidinone, dimethylsulphoxide, benzonitrile, cyclohecyl-pyrrolidinone, N-dodecyl pyrrolidone, benzyl benzoate, benzyl ether bromobenzene, dimethylacetamide, and dimethylformamide.

Each of the 2D nanomaterials341may include one layer or a plurality of layers. For example, each of the 2D nanomaterials341may include tens of layers. Each layer of each of the 2D nanomaterials341may have a thickness that is equal to or less than about several nm. For example, each layer of each of the 2D nanomaterials341may have a thickness that is equal to or less than 2 nm. However, example embodiments are not limited thereto. Each layer of each of the 2D nanomaterials341may have a size that ranges from about tens of nm to hundreds of nm. Each of the 2D nanomaterials341may have any of various planar shapes.

A mixture ratio of the 2D nanomaterials341to the solvent of the ink may range from, but is not limited to, about 1 μg/mL to about 100 mg/mL. The 2D material layer340may be formed by printing the ink on the top surface of the gate insulating layer330to have a desired (and/or alternatively predetermined) shape and then drying the ink. The 2D material layer340may be formed so that at least some of the 2D nanomaterials341overlap one another. As such, a thickness and a size of the 2D material layer341that is formed by using inkjet printing may respectively range from about several nm to about hundreds of nm and may range from about hundreds of nm to about hundreds of μm.

A conductive material (not shown) may be further mixed with the solvent of the ink. The conductive material may include at least one among, for example, graphene, conductive particles, conductive nanotubes, and conductive nanowires. The conductive particles may include at least one selected from the group consisting of, for example, Ag, Au, Pt, Cu, and fullerene, the conductive nanotubes may include, for example, CNTs, and the conductive nanowires may include, for example, Ag nanowires. However, example embodiments are not limited thereto. As such, when the 2D material layer340is formed by using the ink including the 2D nanomaterials341and the conductive material, the conductive material connects the 2D nanomaterials341, thereby increasing conductivity of the 2D material layer341and increasing an on-current of the electronic device.

Also, a dopant (not shown) may be further mixed with the solvent of the ink. As such, when the dopant is further included in the solvent or the 2D nanomaterials341are previously doped, the 2D material layer340may have a desired (and/or alternatively predetermined) conductivity type. For example, the 2D material layer340may include a p-type semiconductor material or an n-type semiconductor material. As such, since the 2D material layer340is doped with desired (and/or alternatively predetermined) impurities, an off-current of the electronic device may be reduced.

Referring toFIG. 6D, the electronic device is completed by forming first and second electrodes351and352on both sides of the 2D material layer340. The first and second electrodes351and352may be respectively a source electrode and a drain electrode. Alternatively, the first and second electrodes351and352may be respectively a drain electrode and a source electrode. The first and second electrodes351and352may be formed by using inkjet printing. In this case, the first and second electrodes351and352may be formed by printing ink including a conductive material on top surfaces of the gate insulating layer330and the 2D material layer340by using an inkjet printing apparatus to have a desired (and/or alternatively predetermined) shape and then drying the ink. The conductive material that is included in the ink may include at least one selected from the group consisting of, for example, graphene, Ag particles, Au particles, Pt particles, Cu particles, CNTs, and Ag nanowires. The first and second electrodes351and352may be formed by using another deposition method, instead of inkjet printing.

A plurality of the electronic devices may be manufactured. In this case, an insulating layer including a low-k dielectric material such as fluorinated graphene or graphene oxide may be formed between the electronic devices. The insulating layer may be formed by using inkjet printing.

As described above, since the gate electrode320, the gate insulating layer330, the 2D material layer340, and the first and second electrodes351and352are formed by using inkjet printing, the electronic device may be simply manufactured. Also, since the 2D material layer340may be formed to have a great size by using inkjet printing, the electronic device may be formed to have a large area.

FIG. 7is a plan view illustrating an electronic device400according to example embodiments.FIG. 8is a cross-sectional view taken along line VIII-VIII′ ofFIG. 7. A transistor device having a top-gate structure is illustrated as the electronic device400inFIGS. 7 and 8.

Referring toFIGS. 7 and 8, the electronic device400includes a 2D material layer440that is provided on a substrate410, a gate insulating layer430, a gate electrode420, and first and second electrodes451and452. The substrate410may be a substrate formed of any of various materials such as a semiconductor substrate, and may be a substrate formed of a flexible material such as a plastic substrate. An insulating layer (not shown) may be further provided on a top surface of the substrate410in order to insulate the substrate410from the 2D material layer440. The insulating layer may include, for example, but is not limited to, silicon oxide or silicon nitride. When the substrate410includes an insulating material, the insulating layer may not be provided on the top surface of the substrate410.

The 2D material layer440that functions as a channel layer is provided on the substrate410. As described above, the 2D material layer440may be formed so that at least some of a plurality of 2D nanomaterials441overlap one another. The 2D nanomaterials440are nano-sized materials having semiconductor characteristics and having a 2D crystal structure.

Each of the 2D nanomaterials441may include one layer or a plurality of layers. For example, each of the 2D nanomaterials441may include tens of layers. Each layer of each of the 2D nanomaterials441may have a thickness that is equal to or less than about several nm and may have a size that ranges from about tens of nm to about hundreds of nm. Each of the 2D nanomaterials441may have any of various planar shapes. The 2D material layer440may be formed by using inkjet printing as described above. A thickness and a size of the 2D material layer440that is formed by using inkjet printing may respectively range from about several nm to about hundreds of nm and range from about hundreds of nm to about hundreds of μm.

The 2D material layer440includes the 2D nanomaterials441having semiconductor characteristics. For example, the 2D nanomaterials441may include at least one selected from the group consisting of TMD, phosphorene (black phosphorus), germanane, and silicene. TMD may include at least one selected from the group consisting of, for example, MoS2, MoSe2, MoTe2, WS2, WSe2, WTe2, TaS2, TaSe2, TiS2, TiSe2, HfS2, HfSe2, SnS2, SnSe2, GeS2, GeSe2, GaS2, GaSe2, Bi2S3, Bi2Se3, and Bi2Te3. As described above, since an on/off current ratio is increased to be equal to or greater than 100 when the 2D material layer440is used as a channel layer of the electronic device400, operation efficiency of the electronic device400may be improved.

The 2D material layer440may further include a material other than the 2D nanomaterials441. For example, the 2D material layer440may include the plurality of 2D nanomaterials441and a conductive material (not shown). The 2D nanomaterials441may be formed so that at least some of the 2D nanomaterials441overlap one another, and the conductive material may be attached to the 2D nanomaterials441and may increase electrical conductivity between the 2D nanomaterials441. The conductive material that is included in the 2D material layer440may include at least one among, for example, graphene, conductive particles, conductive nanotubes, and conductive nanowires. The conductive particles may include at least one selected from the group consisting of, for example, Ag, Au, Pt, Cu, and fullerene. The conductive nanotubes may include, for example, CNTs. The conductive nanowires may include, for example, Ag nanowires.

A dopant (not shown) may be further included in the 2D material layer440that includes the 2D nanomaterials441or both the 2D nanomaterials441and the conductive material. The dopant may be included in ink when the 2D material layer440is formed by using inkjet printing. The 2D nanomaterials441that are included in the 2D material layer440may be previously doped with impurities.

The gate insulating layer430is provided on the substrate410to cover the 2D material layer440. The gate insulating layer430may include any of various insulating materials. For example, the gate insulating layer430may include, but is not limited to, silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, hafnium oxide, and/or insulating polymer. The gate insulating layer430may be formed by using inkjet printing or another deposition method.

The gate electrode420is provided on the gate insulating layer430. The gate electrode420may be disposed to correspond to the 2D material layer440. The gate electrode420may include a conductive material. For example, the gate electrode420may include graphene, CNTs, or a metal such as Ag, Au, Pt, or Cu. The gate insulating layer430may be formed by using inkjet printing or another deposition method.

The first and second electrodes451and452are provided on both sides of the gate electrode420. The first and second electrodes451and452are provided on the gate insulating layer430to be electrically connected to both sides of the 2D material layer440. The first and second electrodes451and452may be respectively a source electrode and a drain electrode. Alternatively, the first and second electrodes451and452may be respectively a drain electrode and a source electrode. The first and second electrodes451and452may include a conductive material, like the gate electrode420. As described below, the first and second electrodes451and452may be formed by using inkjet printing or another deposition method.

FIG. 9is a cross-sectional view illustrating an electronic device500according to example embodiments. A diode device that forms a Schottky junction is illustrated as the electronic device500inFIG. 9.

Referring toFIG. 9, the electronic device500includes first and second electrodes551and552that are spaced part from each other and a 2D material layer540that connects the first and second electrodes551and552. The first and second electrodes541and552may include a metal. The first and second electrodes541and542may be formed by using inkjet printing or another deposition method.

The 2D material layer540may be formed so that at least some of 2D nanomaterials (not shown) having semiconductor characteristics overlap one another. The 2D material layer540may be formed by using inkjet printing as described above. The 2D material layer540has been explained, and thus a detailed explanation thereof will not be given. The 2D material layer540may further include a conductive material (not shown) such as graphene, conductive particles, conductive nanotubes, or conductive nanowires. The 2D material layer540may further include a dopant (not shown). The dopant may be included in ink when the 2D material layer540is formed by using inkjet printing. The 2D nanomaterials that are included in the 2D material layer540may be previously doped with impurities.

As such, since the 2D material layer540has semiconductor characteristics, the 2D material layer540may form a Schottky junction with the first and second electrodes551and552including a metal. That is, a Schottky junction may be formed at a boundary540abetween the first electrode551and the 2D material layer540and a boundary540bbetween the second electrode552and the 2D material layer540.

FIG. 10is a cross-sectional view illustrating an electronic device600according to example embodiments. A diode device that forms a p-n junction is illustrated as the electronic device600inFIG. 10.

Referring toFIG. 10, the electronic device600includes first and second electrodes651and652that are spaced apart from each other and a 2D material layer640that connects the first and second electrodes651and652. The first and second electrodes651and652may include a conductive material. The first and second electrodes651and652may be formed by using inkjet printing or another deposition method.

The 2D material layer640may include a first conductivity type material layer641and a second conductivity type material layer642. The first conductivity type material layer641is provided to electrically connect the first electrode651and the second conductivity type material layer642, and the second conductivity type material layer642is provided to electrically connect the second electrode652and the first conductivity type material layer641. Accordingly, the first and second conductivity type material layers641and642may be provided to partially overlap each other. The first and second conductivity type material layers641and642may be formed by using, for example, inkjet printing.

The first conductivity type material layer641may include 2D nanomaterials and a first conductivity type dopant (not shown). The 2D nanomaterials may be provided so that at least some of the 2D nanomaterials overlap one another. The first conductivity type dopant may be p-type impurities or n-type impurities. When the first conductivity type material layer641is formed by using inkjet printing, the first conductivity type dopant may be included in ink along with the 2D nanomaterials. The 2D nanomaterials may be previously doped with the first conductivity type dopant and then may be mixed with the ink.

The second conductivity type material layer641may include 2D nanomaterials (not shown) and a second conductivity type dopant (not shown). The 2D nanomaterials may be provided so that at least some of the 2D nanomaterials overlap one another. The second conductivity type dopant may be n-type impurities or p-type impurities. In detail, when the first conductivity type dopant is p-type impurities, the second conductivity type dopant may be n-type impurities. When the first conductivity type dopant is n-type impurities, the second conductivity type dopant may be p-type impurities. When the second conductivity type material layer642is formed by using inkjet printing, the second conductivity type dopant may be included in ink along with the 2D nanomaterials. The 2D nanomaterials may be previously doped with the second conductivity type dopant and then may be mixed with the ink. As described above, a p-n junction may be formed at a boundary between the first conductivity type material layer641and the second conductivity type material layer642of the 2D material layer640.

FIG. 11is a cross-sectional view illustrating an electronic device700according to example embodiments. A sensor device that detects a specific gas is illustrated as the electronic device700inFIG. 11.

Referring toFIG. 11, the electronic device700includes first and second electrodes751and752that are spaced apart from each other and a 2D material layer740that connects the first and second electrodes751and752. The first and second electrodes751and752may include a conductive material. The first and second electrodes751and752may be formed by using inkjet printing or another deposition method.

The 2D material layer740may be formed so that at least some of 2D nanomaterials (not shown) having semiconductor characteristics overlap one another. The 2D material layer740may be formed by using inkjet printing as described above. The 2D material layer740has been explained, and thus a detailed explanation thereof will not be given. As such, the 2D material layer740including the 2D nanomaterials having semiconductor characteristics may function as a gas absorber that selectively absorbs a specific gas such as hydrogen or oxygen. Accordingly, in the electronic device700ofFIG. 11, when a specific gas is adsorbed by the 2D material layer740, whether there is the specific gas may be detected by using the first and second electrodes751and752.

As described above, according to example embodiments, since a 2D material layer including 2D nanomaterials having semiconductor characteristics is used as a channel layer, operation efficiency of an electronic device such as a transistor device may be improved. The 2D material layer may be applied to various electronic devices such as a diode device and a sensor device. When the 2D material layer is formed by using inkjet printing, the electronic device may be manufactured to have a large area. In addition, since all elements of the electronic device are formed by using inkjet printing, the electronic device may be simply manufactured.

It should be understood that example embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each device or method according to example embodiments should typically be considered as available for other similar features or aspects in other devices or methods according to example embodiments. While some example embodiments have been particularly shown and described, it will be understood by one of ordinary skill in the art that variations in form and detail may be made therein without departing from the spirit and scope of the claims.