KR102630595B1 - Substrate for Thin Film Transistor And Display Device Of The Same - Google Patents

Abstract

The present invention provides an active layer comprising a carbon allotrope-semiconductor composite consisting of a semiconductor material layer surrounding a carbon allotrope. A thin film transistor array substrate according to an embodiment of the present invention includes a gate electrode, an active layer, a gate insulating film, a source electrode, and a drain electrode. The gate electrode is located on the substrate. The active layer faces the gate electrode and includes carbon allotrope-semiconductor complexes comprised of a semiconductor material layer surrounding at least a portion of the carbon allotrope. The gate insulating film is interposed between the gate electrode and the active layer. The source electrode and drain electrode each contact the active layer.

Description

Thin film transistor array substrate and display device including the same {Substrate for Thin Film Transistor And Display Device Of The Same}

The present invention relates to a thin film transistor array substrate and a display device including the same.

Recently, the importance of display devices (FPD: Flat Panel Display) is increasing along with the development of multimedia. In response to this, liquid crystal display (LCD), plasma display panel (PDP), field emission display (FED), organic light emitting device, etc. Various displays are being put into practical use.

There are two ways to drive a display device: a passive matrix method and an active matrix method using a thin film transistor. While the passive matrix method is operated by forming the anode and cathode to be orthogonal and selecting a line, the active matrix method is operated by connecting a thin film transistor to each pixel electrode and switching it on/off.

In addition to basic thin film transistor characteristics such as electron mobility and leakage current, durability and electrical reliability that can maintain a long lifespan are very important. Here, the active layer of the thin film transistor may be mainly formed of amorphous silicon, polycrystalline silicon, or oxide semiconductor. However, amorphous silicon has the advantage of a simple film formation process and low production cost, but has a disadvantage of low electron mobility of 0.5 cm2/Vs. Oxide semiconductors have an on/off ratio of about 10 ⁸ and low leakage current, but have the disadvantage of having an electron mobility of 10 cm2/Vs, which is lower than that of polycrystalline silicon. Polycrystalline silicon has a fast electron mobility of about 100㎠/Vs, but has the disadvantage of having a low on/off ratio compared to oxide semiconductors and being expensive to apply to large areas. Therefore, research is continuing to improve the characteristics of thin film transistors such as electron mobility, leakage current, and on/off ratio.

The present invention provides a thin film transistor array substrate capable of improving device characteristics by forming an active layer containing a carbon allotrope, and a display device including the same.

To achieve the above object, a thin film transistor array substrate according to an embodiment of the present invention includes a gate electrode, an active layer, a gate insulating film, a source electrode, and a drain electrode. The gate electrode is located on the substrate. The active layer faces the gate electrode and includes carbon allotrope-semiconductor complexes comprised of a semiconductor material layer surrounding at least a portion of the carbon allotrope. The gate insulating film is interposed between the gate electrode and the active layer. The source electrode and drain electrode each contact the active layer.

The active layer is continuously connected from one end of the active layer to the other by intersecting carbon allotrope-semiconductor complexes.

In the active layer, carbon allotrope-semiconductor complexes are arranged irregularly. In the active layer, carbon allotrope-semiconductor complexes are arranged in a network shape.

The diameter of carbon allotropes is 5 to 30 nm. The thickness of the semiconductor material layer is 1 to 20 nm. The thickness of the active layer is 20 to 200 nm.

The carbon allotrope has a one-dimensional or two-dimensional structure, and the carbon allotrope is any one of reduced graphene oxide (rGO), non-oxidized graphene (graphene), graphene nanoribbon, or carbon nanotube (CNT), or a mixture thereof. am. The semiconductor material is one or a mixture of ceramic semiconductors, organic semiconductors, transition metal chalcogenides, or oxide semiconductors.

Additionally, the display device according to an embodiment of the present invention includes a gate electrode, an active layer, a gate insulating layer, a source electrode, a drain electrode, an organic insulating layer, and a pixel electrode. The gate electrode is located on the substrate. The active layer faces the gate electrode and includes carbon allotrope-semiconductor complexes comprised of a semiconductor material layer surrounding at least a portion of the carbon allotrope. The gate insulating film is interposed between the gate electrode and the active layer. The source electrode and drain electrode each contact the active layer. The organic insulating film is located on the source electrode and the drain electrode, and the pixel electrode is located on the organic insulating film.

The display device further includes an organic light emitting diode electrically connected to the pixel electrode, an encapsulation layer positioned on the organic light emitting diode, and a cover window positioned on the encapsulation layer.

The display device further includes a common electrode positioned on the same plane as the pixel electrode or spaced apart from below, and a liquid crystal layer positioned on the common electrode.

The present invention can improve the on-current, on/off ratio, and electron mobility of a thin film transistor by including an active layer containing a carbon allotrope-semiconductor composite made of a semiconductor material layer surrounding a carbon allotrope, and can improve threshold voltage characteristics. There are benefits to this.

1 is a cross-sectional view showing the carbon allotrope-semiconductor composite of the present invention.
Figure 2 is a diagram showing a process for manufacturing the carbon allotrope-semiconductor composite of the present invention.
3 and 4 are diagrams showing a process for manufacturing the carbon allotrope-semiconductor composition of the present invention.
Figure 5 is a cross-sectional view showing a thin film transistor array substrate according to an embodiment of the present invention.
Figure 6 is a plan view showing an active layer according to an embodiment of the present invention.
7 and 8 are cross-sectional views showing active layers according to embodiments of the present invention.
Figure 9 is a cross-sectional view showing a liquid crystal display device according to an embodiment of the present invention.
Figure 10 is a cross-sectional view showing an organic light emitting display device according to an embodiment of the present invention.
11 is a transmission electron microscope image of a carbon allotrope-semiconductor composite.
Figure 12 is a graph showing the results of line profiling from direction A to B in Figure 11.
Figure 13 is a graph showing the current-voltage curve of the thin film transistor manufactured according to Comparative Example 1.
Figure 14 is a graph showing the current-voltage curve of thin film transistors manufactured according to Comparative Examples 2 and 3 and Examples.

Hereinafter, some embodiments of the present invention will be described in detail through illustrative drawings. When adding reference numerals to components in each drawing, it should be noted that identical components are given the same reference numerals as much as possible even if they are shown in different drawings. Additionally, when describing embodiments of the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description will be omitted.

Additionally, when describing the components of the invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and the nature, order, or order of the component is not limited by the term. When a component is described as being “connected,” “coupled,” or “connected” to another component, that component may be directly connected or connected to that other component, but there is another component between each component. It will be understood that elements may be “connected,” “combined,” or “connected.” In the same context, when a component is described as being formed “on” or “under” another component, that component means that it is formed directly on that other component or indirectly through another component. It should be understood as including.

The display device according to the present invention disclosed below may be an organic light emitting display device, a liquid crystal display device, an electrophoretic display device, etc. In the present invention, a liquid crystal display device is explained as an example. A liquid crystal display device consists of a thin film transistor array substrate with a pixel electrode and a common electrode formed on a thin film transistor, a color filter substrate, and a liquid crystal layer sandwiched between the two substrates. In this liquid crystal display device, the common electrode and the pixel electrode are positioned vertically or The liquid crystal is driven by a horizontal electric field. Additionally, the display device according to the present invention can also be used in an organic light emitting display device. For example, an organic light emitting display device includes a first electrode connected to a thin film transistor, a second electrode, and a light emitting layer made of organic material between them. Therefore, holes supplied from the first electrode and electrons supplied from the second electrode combine in the light emitting layer to form excitons, which are hole-electron pairs, and emit light by the energy generated when the excitons return to the ground state. The active layer containing the carbon allotrope of the present invention, which will be described later, can be used in the thin film transistor of the display device described above.

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

The present invention discloses a thin film transistor containing a carbon allotrope and a semiconductor material, and specifically discloses a thin film transistor in which an active layer containing a carbon allotrope and a semiconductor material is formed. Thin film transistors are used as switching or driving elements in display devices.

carbon allotrope

Carbon allotropes disclosed in the present invention represent polycyclic aromatic molecules of carbon atoms covalently bonded to each other. The covalently bonded carbon atoms may form a six-member ring as a repeating unit, and may also include one or more of a five-member ring and a seven-member ring. The carbon allotrope may be a single layer, or may comprise multiple layers of carbon allotrope stacked on top of other layers of carbon allotrope. Carbon allotropes have one-dimensional or two-dimensional structures. The carbon allotrope has a maximum thickness of about 100 nm, specifically about 10 nm to about 90 nm, and more specifically about 20 nm to about 80 nm.

There are four major methods for producing carbon allotropes: physical exfoliation, chemical vapor deposition, chemical exfoliation, or epitaxial synthesis. The physical peeling method is a method of attaching scotch tape to a graphite sample and then removing it to obtain a carbon allotrope sheet detached from the graphite on the surface of the scotch tape. The chemical vapor deposition method adsorbs and decomposes carbon precursors in the form of gas or vapor with high kinetic energy on the surface of the substrate on which carbon allotropes are to be grown, separates them into carbon atoms, and causes the carbon atoms to form interatomic bonds to form crystalline carbon allotropes. It is a way to grow. The chemical exfoliation method utilizes the oxidation-reduction properties of graphite, putting graphite in a mixture of sulfuric acid and nitric acid and attaching carboxyl compounds to the edges of carbon allotrope plates. It is converted to an acid chloride by tinol chloride, and then octadecylamine is used to create the carbon allotrope amide. When this is returned using a solution such as tetrahydrofuran, pulverization occurs and individual carbon allotrope sheets are obtained. Epitaxial synthesis is a method of heating silicon carbide (SiC) to a high temperature of 1,500°C, removing silicon (Si), and obtaining a carbon allotrope by using the remaining carbon (C).

The carbon allotrope of the present invention can be reduced graphene oxide (rGO), non-oxidized graphene, graphene nanoribbon, carbon nanotube (CNT), etc. Reduced graphene oxide is made by reducing graphene oxide (GO). When strong acid is added to graphite, it is oxidized and chemically formed into small particles to produce graphene oxide. It is manufactured by reducing graphene oxide. Non-oxidized graphene refers to a carbon allotrope manufactured by a method excluding the oxidation-reduction process among the above-mentioned carbon allotrope manufacturing methods. Graphene nanoribbons are made by cutting graphene into ribbons with a width of nanometers (nm), and have a certain energy band gap depending on the width. Graphene nanoribbons can be synthesized from monomers containing carbon allotropes or manufactured by cutting carbon nanotubes and spreading them flat. Carbon nanotubes can be single-wall carbon nanotubes (single-wall CNT, SWCNT) or multi-wall carbon nanotubes (multi-wall CNT, MWCNT), and those with semiconductor properties or metallic properties can be used. Carbon nanotubes can also be used. In addition to the types of carbon allotropes described above, known carbon allotrope structures such as graphene nanomesh can be applied to the carbon allotrope of the present invention.

The carbon allotrope of the present invention is used in flake form. Carbon allotrope flakes can be manufactured by using a dispersion of a carbon allotrope in a solvent, coating the dispersion on a substrate, drying the solvent, and then applying physical force. Carbon allotrope flakes can be obtained by applying physical force using methods such as ball mill, bead mill, ultrasonic homogenizer, and stirring.

semiconductor material

The semiconductor material of the present invention may be a ceramic semiconductor, an organic semiconductor, a transition metal chalcogenide compound, or an oxide semiconductor, which can be coated with a solution.

Ceramic semiconductors utilize the electrical properties of ceramics. Ceramics rarely conduct electricity because electrons are bound to certain ions or atoms and cannot move freely. However, when an electric field is applied from the outside, the bound electrons react and regenerate. As the arrangement changes and the state changes, the electrons move. Ceramic semiconductors contain metal elements such as silicon (Si), germanium (Ge), selenium (Se), aluminum (Al), titanium (Ti), and zirconium (Zr), oxygen (O), carbon (C), and nitrogen (N). It is composed of oxides, carbides, and nitrides made by combining with ) etc. A representative ceramic semiconductor is barium titanate (BaTiO ₃ ).

Organic semiconductors are organic compounds with semiconductor properties, including high-molecular organic semiconductors or low-molecular organic semiconductors. Polymer organic semiconductors include F8T2 (Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-bithiophene]), PBDDTBOTPDO (Poly[(5,6-dihydro-5-octyl-4,6-dioxo- 4H-thieno[3,4-C]pyrrole-1,3-diyl){4,8-bis[(2-butyloctyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2 ,6-diyl}]), PBDT-TPD(Poly[[5-(2-ethylhexyl)-5,6-dihydro-4,6-dioxo-4H-thieno[3,4-c]pyrrole-1,3 -diyl][4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl]]), PBDTTT-CF(Poly[1 -(6-{4,8-bis[(2-ethylhexyl)oxy]-6-methylbenzo[1,2-b:4,5-b′]dithiophen-2-yl}-3-fluoro-4-methylthieno [3,4-b]thiophen-2-yl)-1-octanone]), PCDTBT(Poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′- di-2-thienyl-2′,1′,3′-benzothiadiazole)], Poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1 ,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl]), PCPDTBT(Poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta [2,1-b; 3,4-b′]dithiophene)-alt-4,7(2,1,3-benzothiadiazole)]), PFO-DBT(Poly[2,7-(9,9-dioctylfluorene)-alt-4,7 -bis(thiophen-2-yl)benzo-2,1,3-thiadiazole]), PTAA (Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]), Poly[(5,6 -dihydro-5-octyl-4,6-dioxo-4H-thieno[3,4-c]pyrrole-1,3-diyl)[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2 -b:4,5-b′]dithiophene-2,6-diyl]], F8BT(Poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1 ,3]thiadiazol-4,8-diyl)]), P3DDT(Poly(3-dodecylthiophene-2,5-diyl)), P3HT(Poly(3-hexylthiophene-2,5-diyl)), MDMOPPV(Poly[ 2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene]), MEH-PPV(Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]), P3OT(Poly(3-octylthiophene-2,5-diyl)), PTB7(Poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene -2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl})) and the like.

Low-molecular-weight organic semiconductors include, for example, TIPS-pentacene (6,13-Bis(triisopropylsilylethynyl)pentacene), TESPentacene (6,13-Bis((triethylsilyl)ethynyl)pentacene), and DH-FTTF(5,5′-Bis). (7-hexyl-9H-fluoren-2-yl)-2,2′-bithiophene), diF-TES-ADT(2,8-Difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene), DH2T(5,5 ′-Dihexyl-2,2′-bithiophene), DH4T(3,3′′′-Dihexyl-2,2′:5′,2′′:5′′,2′′′-quaterthiophene), DH6T(5 ,5′′′′′-Dihexyl-2,2′:5′,2′′:5′′,2′′′:5′′′,2′′′′:5′′′′,2′ ′′′-sexithiophene), DTS(PTTh2)2(4,4′-[4,4-Bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b′]dithiophene- 2,6-diyl]bis[7-(5′-hexyl-[2,2′-bithiophen]-5-yl)-[1,2,5]thiadiazolo[3,4-c]pyridine], 5, 5′-Bis{[4-(7-hexylthiophen-2-yl)thiophen-2-yl]-[1,2,5]thiadiazolo[3,4-c]pyridine}-3,3′-di-2 -ethylhexylsilylene-2,2′-bithiophene), SMDPPEH(2,5-Di-(2-ethylhexyl)-3,6-bis-(5′′-n-hexyl-[2,2′,5′,2 ′′]terthiophen-5-yl)-pyrrolo[3,4-c]pyrrole-1,4-dione), TES-ADT (5,11-Bis(triethylsilylethynyl)anthradithiophene), etc.

The above-described organic semiconductors may use two or more types of high-molecular organic semiconductors and low-molecular organic semiconductors, or may use different high-molecular organic semiconductors, or may use different low-molecular organic semiconductors.

Transition metal dichalcogenides are materials with semiconductor properties and may be, for example, transition metal sulfide, transition metal selenide, or transition metal telluride. Transition metal chalcogen compounds include, for example, SnSe ₂ , CdSe, ZnSe, ZnTe, MoS ₂ , MoSe ₂ , MoTe ₂ , WS ₂ , WSe ₂ , WTe _{2 ,} etc.

Oxide semiconductors are materials with semiconductor properties that include metals such as gallium (Ga), indium (In), zinc (Zn), tin (Sn), silicon (Si), and zirconium (Zr). It may be an oxide. Examples of oxide semiconductors include IGZO, In ₂ O ₃ , ZnO, IZO, IGO, etc., but are not limited to these and known materials can be used.

Carbon Allotrope-Semiconductor Complex

Figure 1 is a cross-sectional view showing the carbon allotrope-semiconductor composite of the present invention, and Figure 2 is a diagram showing a process for manufacturing the carbon allotrope-semiconductor composite of the present invention.

Referring to FIG. 1, the carbon allotrope-semiconductor composite (CSC) of the present invention includes a carbon allotrope (CM) and a semiconductor material layer (SM) surrounding the carbon allotrope. In one embodiment of the present invention, the carbon allotrope (CM) is a carbon nanotube, which may have hexagonal carbon bonds forming a tubular shape. The semiconductor material layer (SM) forms a shape that surrounds the outer peripheral surface of the carbon allotrope (CM). Therefore, carriers can move quickly in the channel of the active layer using the metallic properties of the carbon allotrope, which can have the effect of reducing the channel length. Additionally, by utilizing the semiconductor properties of semiconductor materials, high mobility characteristics can be exhibited compared to semiconductors forming a heterojunction structure.

The carbon allotrope-semiconductor composite (CSC) of the present invention can be manufactured by the following mechanism.

Referring to Figure 2, the surface of carbon nanotubes (CNTs) is functionalized through acid treatment such as nitric acid (HNO ₃ ). When carbon nanotubes with -COOH groups formed on the surface are placed in water (H ₂ O) and indium oxide (In ₂ O ₃ ) precursors, the carbon nanotubes with -COOH groups formed on the surface and indium oxide (In ₂ O ₃ ) are mixed. It exists in solution in the form When this solution is coated and heated, indium oxide (In ₂ O ₃ ) grows based on the point where the -COOH group was formed. Accordingly, a heterojunction carbon allotrope-semiconductor composite in which indium oxide (In ₂ O ₃ ) is coated on the surface of the carbon nanotube is manufactured.

The carbon allotrope-semiconductor composite described above can be prepared in the form of a composition for coating on a substrate.

3 and 4 are diagrams showing a process for manufacturing the carbon allotrope-semiconductor composition of the present invention.

Referring to Figure 3, a carbon allotrope and a semiconductor material are prepared. Carbon allotropes and semiconductor materials can be prepared in powder form. A carbon allotrope-semiconductor composite composition is prepared by mixing a carbon allotrope and a semiconductor material in a solvent. Unlike the above, referring to FIG. 4, the carbon allotrope-semiconductor composite composition of the present invention can be prepared by mixing a carbon allotrope dispersion with a semiconductor precursor solution containing a semiconductor material. Although not shown, the carbon allotrope-semiconductor composite composition of the present invention may be manufactured by coating a carbon allotrope dispersion on a substrate and then coating a semiconductor precursor solution.

At this time, the solvent is water; Ethanol, methanol, isopropyl alcohol, butanol, 2-ethylhexyl alcohol, methoxypentanol, butoxyethanol, ethoxyethoxy ethanol, butoxyethoxy ethanol, methoxy propoxy propanol, texanol, Alcohols selected from pineol and combinations thereof; tetrahydrofuran (THF); Glycerol, ethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, dihexylene glycol, or alkyl ethers thereof; Glycerin, N-methyl-2-pyrrolidinone (NMP), 2-pyrrolidone, acetylacetone, 1,3-dimethylimidazolinone, thiodiglycol, dimethyl sulfoxid, DMSO), N,N-dimethyl acetamide (DMAc)), dimethylformamide (DMF)), sulfolane, diethanolamine, triethanolamine, and combinations thereof. You can use the above.

In order to favorably disperse the carbon allotrope and semiconductor material, other additives may be added or ultrasonic waves may be irradiated. When irradiating ultrasonic waves to a carbon allotrope-semiconductor composite composition, it is preferable to divide the ultrasonic waves several times and irradiate them. For example, a carbon allotrope is mixed with a semiconductor precursor solution, and strong ultrasonic waves (about 250 W) are irradiated using an ultrasonic disruptor for about 30 minutes. By repeating this process, a carbon allotrope-semiconductor composite composition in which the carbon allotrope is well dispersed can be manufactured.

The amount of carbon allotrope used in the carbon allotrope-semiconductor composition of the present invention may be 0.0001 to 1% by weight based on 100% by weight of the semiconductor precursor solution. Here, if the carbon allotrope is 0.0001% by weight or more based on 100% by weight of the semiconductor precursor solution, the effect of improving electron mobility characteristics can be shown, and if the carbon allotrope is 1% by weight or less based on 100% by weight of the semiconductor precursor solution, the carbon allotrope may be It can improve the dispersibility and improve the coating properties of the composition.

Hereinafter, a thin film transistor and a display device including an active layer using the carbon allotrope-semiconductor composite composition described above will be described.

Figure 5 is a cross-sectional view showing a thin film transistor array substrate according to an embodiment of the present invention, Figure 6 is a plan view showing an active layer according to an embodiment of the present invention, and Figures 7 and 8 are a thin film transistor array substrate according to an embodiment of the present invention. This is a cross-sectional view showing the active layer.

Thin film transistor array substrate

The thin film transistor array substrate disclosed in the present invention is explained as an example of a bottom-gate type thin film transistor in which the gate electrode is located below the active layer. However, the present invention is not limited to this, and the structure of all known thin film transistors, such as a top-gate type thin film transistor in which the gate electrode is located above the active layer, can be applied.

Referring to FIG. 5, the gate electrode 120 is located on the substrate 110. The substrate 110 is made of transparent or opaque glass, plastic, or metal. The gate electrode 120 is made of copper (Cu), molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and tantalum (Ta). and tungsten (W), or an alloy thereof. A gate insulating film 130 that insulates the gate electrode 120 is located on the gate electrode 120. The gate insulating film 130 is made of a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a multilayer thereof.

The active layer 140 is located on the gate insulating film 130. The active layer 140 includes the carbon allotrope-semiconductor composite (CSC) described above.

Referring to FIG. 6, the active layer 140 of the present invention is formed by crossing carbon allotrope-semiconductor composites (CSCs) and continuously connecting them from one end of the active layer 140 to the other end. Here, one end of the active layer 140 refers to an area where carbon allotrope-semiconductor composites (CSCs) are in contact with the source electrode 150a located on one side of the active layer 140, and the other end of the active layer 140 refers to a region of carbon This refers to an area where the allotrope-semiconductor complex (CSC) is in contact with the drain electrode 150b located on the other side of the active layer 140. The carbon allotrope-semiconductor composites (CSCs) are continuously connected from the source electrode 150a to the drain electrode 150b, so that carriers travel through the carbon allotrope (CM) and the semiconductor material layer (SM) of the carbon allotrope-semiconductor composite (CS). You can move along. Therefore, the carbon allotrope-semiconductor composite (CSC) of the present invention can serve as the active layer 140.

In the active layer 140, carbon allotrope-semiconductor composites (CSCs) are arranged irregularly. Here, irregular shape means that it does not have any specific shape and is made up of an irregular shape. For example, carbon allotrope-semiconductor composites (CSCs) can be arranged in an irregular net. However, the carbon allotrope-semiconductor composites (CSCs) of the present invention can be arranged in any shape as long as the carbon allotrope-semiconductor composites (CSCs) are continuously connected to each other and are not particularly limited.

When the carbon allotrope (CM) of the carbon allotrope-semiconductor composite (CSC) of the present invention is a carbon nanotube, the diameter of the carbon nanotube may be 5 to 30 nm. The semiconductor material layer (SM) surrounding the carbon allotrope (CM) may have a thickness of 1 to 20 nm. Here, if the thickness of the semiconductor material layer (SM) is 1 nm or more, the carbon allotrope-semiconductor composite (CSC) can exhibit semiconductor characteristics, and if the thickness of the semiconductor material layer (SM) is 20 nm or less, the electron transfer of the active layer 140 It can prevent the temperature from decreasing.

Accordingly, the thickness of the active layer 140 may be 20 to 200 nm. If the thickness of the active layer 140 is 20 nm or more, the carbon allotrope-semiconductor composite (CSC) overlaps in multiple layers to prevent the carbon allotrope-semiconductor composite (CSC) from being disconnected, and the thickness of the active layer 140 If is 200 nm or less, the threshold voltage characteristics of the active layer 140 can be prevented from being deteriorated.

The structure of the carbon allotrope-semiconductor composite (CSC) constituting the above-described active layer 140 has a different structure depending on the manufacturing method.

One method of manufacturing the active layer 140 is to first form carbon allotropes by coating a carbon allotrope solution on a substrate and heat treating it. Next, a semiconductor solution may be coated on the substrate on which the carbon allotropes are formed to form a semiconductor material layer on the carbon allotropes, thereby forming carbon allotrope-semiconductor composites (CSCs). As shown in FIG. 7, the carbon allotrope-semiconductor composite (CSC) manufactured in this way has carbon allotropes (CMs) placed in contact with the upper surface of the substrate 110, and the carbon allotropes (CMs) exposed above the substrate 110. A semiconductor material layer (SM) is formed. Accordingly, the structure of the carbon allotrope-semiconductor composite (CSC) is such that the semiconductor material layer (SM) surrounds a portion of the carbon allotrope (CM).

Another method of manufacturing the active layer 140 is to manufacture a carbon allotrope and a semiconductor material in one solution, then coat this solution on a substrate and heat treat it to form carbon allotrope-semiconductor composites (CSCs). there is. As shown in FIG. 8, the carbon allotrope-semiconductor composite (CSC) manufactured in this way has a shape in which the semiconductor material layer (SM) is disposed in contact with the upper surface of the substrate 110 and completely surrounds the carbon allotrope (CM).

Methods for coating the carbon allotrope-semiconductor composite composition include spin coating, slit coating, screen printing, and ink-jet printing. The solution may be used to coat the carbon allotrope-semiconductor composite composition. Any coating method can be applied. The carbon allotrope-semiconductor composite is heat treated at 250°C for 2 hours to remove the solvent. Additionally, the active layer 140 of the present invention can be manufactured by patterning the carbon allotrope-semiconductor composite using photolithography.

Referring again to FIG. 5, a source electrode 150a contacting one side of the active layer 140 and a drain electrode 150b contacting the other side of the active layer 140 are located on the active layer 140. . The source electrode 150a and the drain electrode 150b may be made of a single layer or multiple layers. In the case of a single layer, molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), It may be made of any one selected from the group consisting of nickel (Ni), neodymium (Nd), and copper (Cu), or an alloy thereof. In addition, when the source electrode 150a and the drain electrode 150b are multilayered, they are a double layer of molybdenum/aluminum-neodymium, molybdenum/aluminum, or titanium/aluminum, or a double layer of molybdenum/aluminum-neodymium/molybdenum, molybdenum/aluminum/molybdenum, or titanium. It can be made of a triple layer of /aluminum/titanium.

The active layer 140 of the present invention described above is formed of carbon allotrope-semiconductor composites (CSCs) composed of a semiconductor material layer surrounding a carbon allotrope. When a voltage is applied to the source electrode 150a and the drain electrode 150b of the active layer 140 manufactured in this way, carrier electrons and holes move into the channel of the active layer 140. At this time, since the active layer 140 is composed of a carbon allotrope and a semiconductor material layer, electrons and holes move very quickly in the carbon allotrope and move from the semiconductor material layer according to the electron mobility of the semiconductor material layer. Electrons and holes can move along the semiconductor material layer and carbon allotropes, greatly improving electron mobility. In particular, semiconductor materials have the characteristic of reducing electron mobility due to scattering, a scattering phenomenon that occurs when electrons move, but carbon allotropes have almost no scattering phenomenon occurring inside the carbon allotrope, so there is concern that electron mobility will be reduced. can be removed.

Hereinafter, with reference to FIGS. 9 and 10, a display device including the thin film transistor array substrate of the present invention will be described. In the following, a display device including a thin film transistor array substrate according to the above-described embodiment will be disclosed, and redundant description will be omitted. FIG. 9 is a cross-sectional view showing a liquid crystal display device according to an embodiment of the present invention, and FIG. 10 is a cross-sectional view showing an organic light emitting display device according to an embodiment of the present invention.

display device

Referring to FIG. 9, an organic insulating film 160 is located on the source electrode 150a and the drain electrode 150b. The organic insulating film 160 is used to flatten the lower step and may be made of organic materials such as photo acryl, polyimide, benzocyclobutene resin, or acrylate. there is. The organic insulating film 160 includes a via hole 165 exposing the drain electrode 150b. Although not shown, a passivation film made of silicon oxide (SiOx), silicon nitride (SiNx), or a multilayer thereof may be positioned on the source electrode 150a and the drain electrode 150b.

The pixel electrode 170 and the common electrode 180 are located on the organic insulating film 160. The pixel electrode 170 is connected to the drain electrode 150b through the via hole 165 formed in the organic insulating film 160. The pixel electrode 160 is made of a transparent and conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). The common electrode 180 is made of the same material as the pixel electrode 170. The pixel electrode 170 and the common electrode 180 are arranged alternately to form a horizontal electric field between the pixel electrode 170 and the common electrode 180.

In an embodiment of the present invention, an in-plane switching (IPS) liquid crystal display device in which a pixel electrode and a common electrode are located on the same plane is described as an example. However, the present invention is not limited to this, and the common electrode may be located below the pixel electrode, or the common electrode may be located on the color filter array substrate facing the thin film transistor array substrate.

Meanwhile, referring to FIG. 10, the display device of the present invention may be an organic light emitting display device including an organic light emitting diode. In more detail, the organic insulating film 160 is located on the source electrode 150a and the drain electrode 150b. The organic insulating film 160 includes a via hole 165 exposing the drain electrode 150b.

The pixel electrode 170 is located on the organic insulating film 160. The pixel electrode 170 is connected to the drain electrode 150b through the via hole 165 formed in the organic insulating film 160. The bank layer 175 is located on the pixel electrode 170. The bank layer 175 may be a pixel defining layer that exposes a portion of the pixel electrode 170 to define a pixel. The organic layer 190 is located on the bank layer 175 and the exposed pixel electrode 170. The organic layer 190 includes a light emitting layer that emits light by combining electrons and holes, and may include a hole injection layer, a hole transport layer, an electron transport layer, or an electron injection layer. The counter electrode 200 is located on the substrate 110 on which the organic layer 190 is formed. The counter electrode 200 is a cathode electrode and may be made of magnesium (Mg), calcium (Ca), aluminum (Al), silver (Ag), or an alloy thereof with a low work function. Accordingly, an organic light emitting diode (OLED) is configured including a pixel electrode 170, an organic layer 190, and a counter electrode 200.

The encapsulation layer 210 is located on the substrate 110 on which the organic light emitting diode (OLED) is formed. The encapsulation layer 210 encapsulates the substrate 110 including the underlying organic light emitting diode (OLED) and may be made of an inorganic film, an organic film, or a multilayer structure thereof. A cover window 220 is located on the encapsulation layer 210 to form an organic light emitting display device.

Hereinafter, an experimental example of an active layer including a carbon allotrope-semiconductor composite consisting of a semiconductor material layer surrounding a carbon allotrope according to an embodiment of the present invention will be disclosed. The following experimental example is only an example of the present invention and the present invention is not limited thereto.

Experiment 1: active layer Composition analysis

A solution in which acid-treated carbon nanotubes were dispersed in a solvent in which an indium oxide (In ₂ O ₃ ) precursor was dissolved was dropped onto a grid and then heat-treated at 250 to 300 degrees. The carbon allotrope-semiconductor complex was analyzed using transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy (EDS).

FIG. 11 is a transmission electron microscope image of a carbon allotrope-semiconductor composite, and FIG. 12 is a graph showing the results of line profiling in the direction A to B of FIG. 11.

Referring to FIG. 11, it was confirmed that a rod-shaped carbon allotrope-semiconductor composite was manufactured.

Referring to FIG. 12, the diameter of the carbon allotrope-semiconductor composite was found to be about 40 nm, and it was confirmed that the ratio of carbon was small and the ratio of indium and oxygen was mostly on the surface of the carbon allotrope-semiconductor composite. Accordingly, it was confirmed that the form of the carbon allotrope-semiconductor composite was indium oxide (In ₂ O ₃ ) composed of indium and oxygen surrounding a carbon nanotube.

Experiment 2: thin film transistor evaluation

<Comparative Example 1>

A bottom gate type thin film transistor having the structure of FIG. 5 described above was manufactured. At this time, the active layer was formed by coating IGZO through a solution process.

<Comparative Example 2>

Under the same process conditions as in Comparative Example 1 described above, a thin film transistor was manufactured except that carbon nanotubes were coated using a solution process to form an active layer.

<Comparative Example 3>

A thin film transistor was manufactured under the same process conditions as in Comparative Example 1 described above, except that indium oxide (In ₂ O ₃ ) was coated using a solution process to form an active layer.

<Example>

Carbon nanotubes were spin-coated on the substrate on which the gate electrode and gate insulating film were formed and then dried at about 100 degrees. A substrate coated with carbon nanotubes was dipped into a nitric acid (HNO ₃ ):sulfuric acid (H ₂ SO ₄ ) (1:3) solution and left for about 1 hour. Afterwards, the acid was removed by washing with DI water, and moisture was removed using a nitrogen (N ₂ ) gun or an air gun. Indium nitrate hydrate was dissolved in water to create a solution capable of forming indium oxide (In ₂ O ₃ ), and then this solution was spin-coated or dipped onto a carbon nanotube substrate. Next, heat treatment was performed in an air atmosphere at 250 degrees for about 1 hour and 30 minutes to form an active layer of a carbon allotrope-semiconductor composite made of indium oxide surrounding the carbon nanotubes. Then, a thin film transistor was manufactured by forming source electrodes and drain electrodes on both sides of the active layer.

The current-voltage curve of the thin film transistor manufactured according to the above-mentioned Comparative Example 1 was measured and shown in FIG. 13, and the current-voltage curve of the thin film transistor manufactured according to Comparative Examples 2, 3 and Examples was measured and shown in FIG. 14. The threshold voltage, on current, and on/off ratio are shown in Table 1 below.

Comparative example 2 Comparative Example 3 Example Threshold voltage (Vth, V) - -15 -5 On Current - 5× ^10-6 1× ^10-6 On/off ratio - ~10 ² ~10 ⁵

Referring to FIG. 13, Comparative Example 1, in which IGZO was produced as an active layer through a solution process ^{, showed low on-current characteristics of a thin film transistor of about 1×10 -8 .}

Referring to FIG. 14 and Table 1, Comparative Example 2, which had an active layer made only of carbon nanotubes, was not driven as a thin film transistor. Comparative Example 3, which has an active layer made of indium oxide (In ₂ O ₃ ) alone, had a threshold voltage of -15 V, an on current of 5×10 ^-6 , and an on/off ratio of 10 ² or less. In the case of Comparative Example 3, since there was no zinc (Zn) and gallium (Ga), the off-current was high and saturation was poor.

On the other hand, the example having an active layer of a carbon allotrope-semiconductor composite made of indium oxide surrounding a carbon nanotube had a threshold voltage of -5V, an on current of 1×10 ^-6 , and an on/off ratio of 10 ⁵ or less. Accordingly, it was confirmed that the thin film transistor of the example exhibited a good threshold voltage, an increase in on-current, and an improvement in the on/off ratio.

Therefore, the present invention can improve the on current, on/off ratio, and electron mobility of a thin film transistor by including an active layer containing a carbon allotrope-semiconductor composite made of a semiconductor material layer surrounding a carbon allotrope, and improve the threshold voltage characteristics. There are benefits that can be improved.

Through the above-described content, those skilled in the art will be able to see that various changes and modifications can be made without departing from the technical idea of the present invention. For example, the x-axis direction or y-axis direction described in the embodiment of the present invention can be changed to opposite directions, and the size, number, and shape of the touch driving electrodes and touch sensing electrodes that make up the common electrode , the positions of the touch driving lines or touch sensing lines connected to each touch electrode can be arbitrarily and appropriately changed, and are not limited to those described in the embodiments of the present invention. Therefore, the technical scope of the present invention should not be limited to what is described in the detailed description of the invention, but should be defined by the scope of the patent claims.

110: substrate 120: gate electrode
130: gate insulating film 140: active layer
150a: source electrode 150b: drain electrode
SM: semiconductor material layer CM: carbon allotrope
CSC: Carbon Allotrope-Semiconductor Composite

Claims (22)

Board;
A gate electrode located on the substrate;
an active layer facing the gate electrode and including carbon allotrope-semiconductor composites made of a semiconductor material layer surrounding at least a portion of the carbon allotrope;
a gate insulating film interposed between the gate electrode and the active layer; and
Includes a source electrode and a drain electrode each in contact with the active layer,
The carbon allotrope-semiconductor composite,
A thin film transistor array substrate wherein the carbon allotrope is disposed in contact with the upper surface of the gate insulating film, and the semiconductor material layer is formed on the carbon allotrope to surround a portion of the carbon allotrope. According to claim 1,
The active layer is a thin film transistor array substrate in which the carbon allotrope-semiconductor complexes cross each other and are continuously connected from one end to the other end of the active layer. According to claim 1,
The active layer is a thin film transistor array substrate in which the carbon allotrope-semiconductor complexes are irregularly arranged. According to clause 3,
The active layer is a thin film transistor array substrate in which the carbon allotrope-semiconductor complexes are arranged in a net shape. According to claim 1,
A thin film transistor array substrate wherein the carbon allotrope has a diameter of 50 to 30 nm. According to claim 1,
A thin film transistor array substrate wherein the semiconductor material layer has a thickness of 1 to 20 nm. According to claim 1,
A thin film transistor array substrate wherein the active layer has a thickness of 20 to 200 nm. According to claim 1,
The carbon allotrope is a thin film transistor array substrate having a one-dimensional or two-dimensional structure. According to claim 1,
The carbon allotrope is a thin film transistor array substrate that is one of reduced graphene oxide (rGO), non-oxidized graphene (graphene), graphene nanoribbon, or carbon nanotube (CNT), or a mixture thereof. According to claim 1,
A thin film transistor array substrate wherein the semiconductor material is any one of a ceramic semiconductor, an organic semiconductor, a transition metal chalcogenide compound, or an oxide semiconductor, or a mixture thereof. Board;
A gate electrode located on the substrate;
an active layer facing the gate electrode and including carbon allotrope-semiconductor composites made of a semiconductor material layer surrounding at least a portion of the carbon allotrope;
a gate insulating film interposed between the gate electrode and the active layer;
a source electrode and a drain electrode each contacting the active layer;
an organic insulating film positioned on the source electrode and the drain electrode; and
Includes a pixel electrode located on the organic insulating film,
The carbon allotrope-semiconductor composite,
A display device in which the carbon allotrope is disposed in contact with an upper surface of the gate insulating film, and the semiconductor material layer is formed on the carbon allotrope to surround a portion of the carbon allotrope. According to claim 11,
The active layer is a display device in which the carbon allotrope-semiconductor complexes intersect each other and are continuously connected from one end to the other end of the active layer. According to claim 11,
The active layer is a display device in which the carbon allotrope-semiconductor complexes are irregularly arranged. According to claim 13,
The active layer is a display device in which the carbon allotrope-semiconductor complexes are arranged in a net shape. According to claim 11,
A display device wherein the carbon allotrope has a diameter of 5 to 30 nm. According to claim 11,
A display device wherein the semiconductor material layer has a thickness of 1 to 20 nm. According to claim 11,
A display device wherein the active layer has a thickness of 20 to 200 nm. According to claim 11,
A display device in which the carbon allotrope has a one-dimensional or two-dimensional structure. According to claim 11,
A display device in which the carbon allotrope is any one of reduced graphene oxide (rGO), non-oxidized graphene (graphene), graphene nanoribbon, or carbon nanotube (CNT), or a mixture thereof. According to claim 11,
A display device in which the semiconductor material is any one or a mixture of a ceramic semiconductor, an organic semiconductor, a transition metal chalcogenide, or an oxide semiconductor. According to claim 11,
an organic light emitting diode electrically connected to the pixel electrode;
an encapsulation layer located on the organic light emitting diode; and
A display device further comprising a cover window located on the encapsulation layer. According to claim 11,
a common electrode positioned spaced apart from or below the same plane as the pixel electrode; and
A display device further comprising a liquid crystal layer located on the common electrode.

Images