KR20110045252A - Thin film transistor and flat panel display device having same - Google Patents

Abstract

PURPOSE: A thin film transistor and flat panel display device with the same are provided to use a graphene layer as a semiconductor layer, thereby enhancing electrical features. CONSTITUTION: A substrate supports a thin film transistor. A semiconductor layer is composed of a graphene layer and a control layer. The size of grapheme is larger than 1 mm∧2. A metal atomic layer is interposed between the graphene layer and the control layer. A light emitting device is electrically connected to the thin film transistor.

Description

Thin film transistor, and a flat panel display including the same {Thin film transistor, and a flat panel display therewith}

A thin film transistor and a flat panel display device having the same are disclosed, and the thin film transistor can improve electrical characteristics by using graphene as a semiconductor layer.

Thin film transistors used in flat panel display devices such as liquid crystal display devices, organic electroluminescent display devices, or inorganic electroluminescent display devices (hereinafter referred to as TFTs) are used to drive switching elements and pixels that control the operation of each pixel. Used as a drive element.

Such a TFT has a semiconductor layer having a source / drain region doped with a high concentration of impurities and a channel region formed between the source / drain regions, the gate being insulated from the semiconductor layer and located in a region corresponding to the channel region. And a source / drain electrode in contact with the source / drain region, respectively.

However, the source / drain electrodes are usually made of a metal having a low work function to smoothly flow electric charges. Due to the high contact resistance of the region where the metal and the semiconductor layer are in contact, the characteristics of the device are deteriorated. Furthermore, there is a problem that power consumption is increased.

Accordingly, a technical problem to be solved in one embodiment is to provide a thin film transistor having improved electrical characteristics by improving a structure of a semiconductor layer.

Another technical problem to be solved in one embodiment is to provide a flat panel display device having the thin film transistor.

According to one aspect, at least three gate terminals, a source electrode, a drain electrode, an insulator layer, and a semiconductor layer are provided on a substrate, and the thin film transistor which controls the current between the source and the drain by applying a voltage to the gate electrode, The semiconductor layer provides a thin film transistor having a graphene layer and a control layer.

According to one aspect, at least three gate terminals, a source electrode, a drain electrode, an insulator layer, and a semiconductor layer are provided on a substrate, and the thin film transistor which controls the current between the source and the drain by applying a voltage to the gate electrode, A thin film transistor including a graphene layer and a control layer; And a light emitting device electrically connected to the thin film transistor.

The term "graphene" as used herein refers to a plurality of carbon atoms covalently linked to each other to form a polycyclic aromatic molecule, wherein the carbon atoms linked to the covalent bond form a six-membered ring as a basic repeating unit, It is also possible to further include a 5-membered ring and / or a 7-membered ring. As a result, the graphene appears as a single layer of covalently bonded carbon atoms (usually sp ² bonds). The graphene may be formed of a single layer, but they may be stacked with each other to form a plurality of layers, and may form a thickness up to 100 nm.

The graphene has an abnormal half-integer quantum hall effect with respect to electrons and holes. Also, the graphene has a high electron mobility of about 20,000 to 50,000 cm ² / Vs. Known. In addition, since the electrical characteristics are changed according to the crystal orientation of the graphene layer having a predetermined thickness, the user can express the electrical characteristics in the selection direction, and thus there is an advantage that the device can be easily designed.

Hereinafter, the device configuration of a thin film transistor according to an embodiment will be described.

In a device configuration of a thin film transistor according to an embodiment, at least three terminals of a gate electrode, a source electrode, a drain electrode, an insulator layer, and a semiconductor layer are provided on a substrate, and a voltage between the source and the drain is applied to the gate electrode. The thin film transistor controlled by this is not limited, It may have a well-known element structure. Among these, elements A to D are shown in Figs. 1 to 4 as device configurations of representative thin film transistors. As described above, several configurations are known depending on the position of the electrode, the stacking order of the layers, and the like, and the thin film transistor has a field effect transistor (FET) structure. The thin film transistor has a semiconductor layer (graphene layer and a control layer), a source electrode and a drain electrode formed to face each other at a predetermined interval, and a gate electrode formed at a predetermined distance from the source electrode and the drain electrode, respectively, and the gate electrode. The current flowing between the source and drain electrodes is controlled by applying a voltage to the. Here, the distance between the source electrode and the drain electrode is determined according to the use of the thin film transistor, and is usually 0.1 to 1 mm, for example, 1 to 100 m, or 5 to 100 m.

Referring to device B of FIG. 2 in more detail as an example among the devices A to D, the thin film transistor of device B has a gate electrode and an insulator layer in this order on a substrate, and a pair of sources formed at predetermined intervals on the insulator layer. It has an electrode and a drain electrode, and a semiconductor layer is formed on it. The semiconductor layer forms a channel region, and the current flowing between the source electrode and the drain electrode is controlled by a voltage applied to the gate electrode, thereby operating on / off.

(Semiconductor layer)

The semiconductor layer is composed of a graphene layer and a control layer.

The graphene layer used in the semiconductor layer may have an area of 1 mm ² or more, for example, 1 mm ² to 3 cm ² . Although the film thickness of the said graphene layer is not specifically limited, 0.5 nm-1 micrometer or 2 nm-250 nm are mentioned.

An example provided with the semiconductor layer is shown in FIG. As shown in FIG. 5, the control layer is provided adjacent to the semiconductor layer, and may include one or more selected from oxides, nitrides, and sulfides. Examples of the sulfide include zinc sulfide (ZnS), cadmium sulfide (CdS), calcium sulfide (CaS), yttrium sulfide (Y ₂ S ₃ ), gallium sulfide (Ga ₂ S ₃ ), strontium sulfide (SrS), and barium sulfide (BaS). And the like, and zinc oxide (ZnO), yttrium oxide (Y ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), and the like. Moreover, as nitride, aluminum nitride (AlN), gallium nitride (GaN), indium nitride (InN), etc. are mentioned.

A metal atomic layer may be further formed between the graphene layer and the adjustment layer, an example of which is shown in FIG. 6. Such an atomic layer may have a thickness of one to three layers based on the atom.

The graphene layer may be used by preparing a graphene sheet and cutting the graphene sheet into a predetermined size, or may be prepared by growing directly on a substrate. A method for producing such graphene sheet is disclosed in Korean Patent Application No. 10-2008-0023457, which is incorporated herein.

In order to form a film of the same type as the control layer on the graphene, for example, an ultra-high vacuum method may be used to form a metal atomic layer on the graphene layer and then oxidize it. For example, Al may be formed in one to three layers on the graphene layer by using an ultrahigh vacuum method, and then oxidized under Al atmosphere to form a control layer composed of an oxide.

The stacking order of the graphene layer and the control layer may vary depending on the device to be used, and may be stacked in the order of the graphene layer-controlling layer or in the order of the control layer-graphene layer.

(Board)

The substrate in the thin film transistor serves to support the structure of the thin film transistor, and as a material, an inorganic compound such as metal oxide or nitride, a plastic film (PET, PES, PC), a metal substrate or a composite thereof as well as glass Or a laminate or the like can also be used. In addition, when the structure of a thin film transistor can fully be supported by components other than a board | substrate, it is also possible not to use a board | substrate. In addition, as a material of a substrate, a silicon (Si) wafer is often used. In this case, Si itself can be used as the gate electrode and the substrate. It is also possible to oxidize the surface of Si to form SiO ₂ and to utilize it as an insulating layer. In this case, metal layers, such as Au, are formed into a film as a lead wire connection electrode on the Si substrate of a board | substrate and a gate electrode.

(electrode)

The material of the gate electrode, the source electrode, and the drain electrode in the thin film transistor according to one embodiment is not particularly limited as long as it is a conductive material. Platinum, gold, silver, nickel, chromium, copper, iron, tin, antimony lead, tantalum Rum, indium, palladium, tellurium, rhenium, iridium, aluminum, ruthenium, germanium, molybdenum, tungsten, tin oxide antimony, indium tin oxide (ITO), fluorine-doped zinc oxide, zinc, carbon, graphite, Glassy carbon, silver paste and carbon paste, lithium, beryllium, sodium, magnesium, potassium, calcium, scandium, titanium, manganese, zirconium, gallium, niobium, sodium, sodium-potassium alloys, magnesium, lithium, aluminum, magnesium / copper Mixtures, magnesium / silver mixtures, magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide mixtures, lithium / aluminum mixtures, and the like, The film formation by a sputtering method or a vacuum vapor deposition method can form the electrode.

In the thin film transistor according to one embodiment, as the source electrode and the drain electrode, one formed by using a fluid electrode material such as a solution, paste, ink, and dispersion liquid containing the conductive material may be used. Moreover, as a solvent or a dispersion medium, in order to suppress the damage to an organic semiconductor, it is preferable that it is a solvent or dispersion medium containing 60 mass% or more, Preferably it is 90 mass% or more. As a dispersion containing metal microparticles | fine-particles, a well-known electrically conductive paste etc. can also be used, for example, It is preferable if it is a dispersion containing metal microparticles | fine-particles of 0.5 nm-50 nm and 1 nm-10 nm normally. Examples of the metal fine particles include platinum, gold, silver, nickel, chromium, copper, iron, tin, antimony lead, tantalum, indium, palladium, tellurium, rhenium, iridium, aluminum, ruthenium, germanium, and mol. Ribdenum, tungsten, zinc and the like can be used.

It is preferable to form an electrode using the dispersion which disperse | distributed these metal microparticles | fine-particles mainly using the dispersion stabilizer which consists of organic materials in water and the dispersion medium which is arbitrary organic solvents. As a method for producing a dispersion of the metal fine particles, a physical production method such as evaporation in a gas, a sputtering method, a metal vapor synthesis method, or a chemical production method of producing metal fine particles by reducing metal ions in a liquid phase such as a colloid method or a coprecipitation method may be employed. For example.

The electrode is molded using these metal fine particle dispersions, and the solvent is dried. Then, the metal fine particles are thermally fused by heating in a shape in a range of 100 ° C to 300 ° C, for example, 150 ° C to 200 ° C, if necessary. An electrode pattern having a desired shape can be formed.

Moreover, as a material of a gate electrode, a source electrode, and a drain electrode, the well-known conductive polymer which improved conductivity by doping etc. can be used, for example, conductive polyaniline, conductive polypyrrole, conductive polythiophene (polyethylene dioxythiophene and polystyrene sulfonate) Complexes of phonic acid), and complexes of polyethylenedioxythiophene (PEDOT) and polystyrenesulfonic acid are also suitably used. These materials can reduce the contact resistance between the semiconductor layer of the source electrode and the drain electrode.

It is preferable that the material which forms a source electrode and a drain electrode is small in electrical resistance in the contact surface with a semiconductor layer among the above-mentioned examples. The electrical resistance at this time corresponds to the field effect mobility when the current control device is manufactured, and in order to obtain large mobility, it is necessary that the resistance is as small as possible. This is generally determined by the magnitude relationship between the work function of the electrode material and the energy level of the organic semiconductor layer.

If the work function W of the electrode material is a, the ionization potential Ip of the semiconductor layer is b, and the electron affinity Af of the semiconductor layer is c, it is preferable to satisfy the following relational expression. Here, a, b and c are all positive values based on the vacuum level.

In the case of a p-type thin film transistor, the thing of b-a <1.5eV or b-a <1.0eV is mentioned, for example. If the above relationship can be maintained in the relationship with the semiconductor layer, a high-performance device can be obtained. In particular, a work function of the electrode material can be selected as large as possible, and a work function of 4.0 eV or more or a work function of 4.2 eV or more can be used. have.

High work function metals are mainly Ag (4.26, 4.52, 4.64, 4.74 eV), Al (4.06, 4.24, 4.41 eV), Au (5.1, 5.37, 5.47 eV), Be (4.98 eV), Bi (4.34 eV), Cd (4.08 eV), Co (5.0 eV), Cu (4.65 eV), Fe (4.5, 4.67, 4.81 eV), Ga (4.3 eV), Hg (4.4 eV), Ir (5.42, 5.76 eV), Mn (4.1 eV), Mo (4.53, 4.55, 4.95 eV), Nb (4.02, 4.36, 4.87 eV), Ni (5.04, 5.22, 5.35 eV), Os (5.93 eV), Pb (4.25 eV), Pt (5.64 eV) , Pd (5.55 eV), Re (4.72 eV), Ru (4.71 eV), Sb (4.55, 4.7 eV), Sn (4.42 eV), Ta (4.0, 4.15, 4.8 eV), Ti (4.33 eV), V (4.3 eV), W (4.47, 4.63, 5.25 eV) and Zr (4.05 eV) can be used. For example, precious metals (Ag, Au, Cu, Pt), Ni, Co, Os, Fe, Ga, Ir, Mn, Mo, Pd, Re, Ru, V, W can be used. Other than metals, conductive polymers such as ITO, polyaniline or PEDOT: PSS and carbon can be used. As an electrode material, even if it contains 1 type or multiple of these high work function substances, if a work function satisfy | fills the said Formula, it will not restrict | limit in particular.

In the case of an n-type thin film transistor, a-c <1.5eV or a-c <1.0eV may be used. A high performance device can be obtained if the above relationship can be maintained in the relationship with the semiconductor layer, but in particular, a work function of the electrode material can be selected as small as possible, and a work function of 4.3 eV or less or 3.7 eV or less can be used. .

Specific examples of the low work function metal include Ag (4.26 eV), Al (406, 4.28 eV), Ba (2.52 eV), Ca (2.9 eV), Ce (2.9 eV), Cs (1.95 eV), Er (2.97). eV), Eu (2.5 eV), Gd (3.1 eV), Hf (3.9 eV), In (4.09 eV), K (2.28 eV), La (3.5 eV), Li (2.93 eV), Mg (3.66 eV) , Na (2.36eV), Nd (3.2eV), Rb (4.25eV), Sc (3.5eV), Sm (2.7eV), Ta (4.0, 4.15eV), Y (3.1eV), Yb (2.6eV) And Zn (3.63 eV). Among these, Ba, Ca, Cs, Er, Eu, Gd, Hf, K, La, Li, Mg, Na, Nd, Rb, Y, Yb and Zn are mentioned as an example. As the electrode material, even if one or more of these low work function materials are contained, the work function is not particularly limited as long as the work function satisfies the above formula. However, since the low work function metal easily deteriorates when it comes into contact with moisture or oxygen in the air, it is preferable to coat it with a stable metal in air such as Ag or Au as necessary. The film thickness required for coating is required to be 100 nm or more, and as the film thickness becomes hot, the film thickness can be protected from oxygen or water. However, in practical use, the film thickness can be 1 m or less for reasons of increasing productivity.

The electrode is formed by, for example, vapor deposition, electron beam deposition, sputtering, atmospheric plasma method, ion plating, chemical vapor deposition, electrodeposition, electroless plating, spin coating, printing or ink jet. Moreover, as a method of patterning as needed, the method of electrode formation of the electroconductive thin film formed using the said method using the well-known photolithographic method or the lift-off method, and thermal transfer on metal foils, such as aluminum and copper, , Ink jet, or the like, is a method of forming and etching a resist. Moreover, the solution or dispersion liquid of a conductive polymer, the dispersion liquid containing metal microparticles | fine-particles, etc. can also be patterned directly by the inkjet method, and can also be formed from a coating film by lithography, laser polishing, etc. Moreover, the method of patterning the conductive ink, conductive paste, etc. containing a conductive polymer, metal fine particles, etc. by printing methods, such as a convex plate, a recessed plate, a flat plate, and screen printing, can also be used.

The film thickness of the electrode thus formed is not particularly limited as long as the current passes, but is, for example, in the range of 0.2 nm to 10 μm or 4 nm to 300 nm. If it is in this range, as a film thickness becomes thin, resistance becomes high and a voltage drop does not generate | occur | produce. Moreover, since it is not too thick, it does not take time to form a film, and when laminated | stacking another layer, such as a protective layer and an organic-semiconductor layer, a laminated film can be made smoothly without a step.

Further, in the thin film transistor according to one embodiment, for example, a buffer layer may be provided between the semiconductor layer, the source electrode, and the drain electrode in order to improve the injection efficiency. As the buffer layer, a compound having an alkali metal or alkaline earth metal ion bond such as LiF, Li ₂ O, CsF, NaCO ₃ , KCl, MgF ₂ , CaCO _3, etc., used for the cathode of the organic EL device may be used as the buffer layer. Can be. Moreover, the compound used as an electron injection layer and an electron carrying layer can also be inserted in organic electroluminescent element, such as Alq (tris (8-quinolinol) aluminum complex).

For p-type thin film transistors, cyano compounds such as FeCl ₃ , TCNQ, F4-TCNQ, HAT, CF _x or GeO ₂ , SiO ₂ , MoO ₃ , V ₂ O ₅ , VO ₂ , V ₂ O ₃ , MnO, Mn _{3 O 4, ZrO 2, WO} 3, TiO 2, in 2 O 3, ZnO, NiO, HfO 2, Ta 2 O 5, ReO 3, PbO 2 , such as an alkali metal, a metal other than alkaline earth metal oxide, of ZnS, Inorganic compounds such as ZnSe are preferred. These oxides in most cases cause oxygen deficiency, which is suitable for hole injection. TPD (N, N'-bis (3-methylphenyl) -N, N'-diphenyl- (1,1'-biphenyl) -4,4'-diamine) or NPD (4,4'-bis Amine compounds, such as [N- (1-naphthyl) -N-phenylamino] biphenyl), and compounds used as a hole injection layer and a hole transport layer in organic electroluminescent elements, such as CuPc (copperphthalocyanine), may be sufficient have. Moreover, what consists of two or more types of said compounds can be used.

The buffer layer has the effect of lowering the threshold voltage by driving the carrier injection barrier and driving the transistor at low voltage. The buffer layer may be thin between the electrode and the organic semiconductor layer, and the thickness thereof is 0.1 nm to 30 nm, or 0.3 nm to 20 nm.

(Insulator layer)

The material of the insulator layer in the thin film transistor according to one embodiment is not particularly limited as long as it is electrically insulating and can be formed as a thin film. Metal oxides (including silicon oxides) and metal nitrides (silicon nitrides) Material having an electrical resistivity of 10 OMEGA cm or more at room temperature, such as a polymer, an organic low molecule, and the like, and for example, an inorganic oxide film having a high dielectric constant can be used.

The inorganic oxide may be silicon oxide, aluminum oxide, tantalum oxide, titanium oxide, tin oxide, vanadium oxide, barium strontium titanate, barium titanate zirconate, lead titanate zirconate, lead lanthanum titanate, strontium titanate, Barium titanate, barium magnesium fluoride, lanthanum oxide, fluorine oxide, magnesium oxide, bismuth oxide, bismuth titanate, niobium oxide, strontium bismuth titanate, strontium bismuth tantalate, bismuth pentoxide, bismuth niobate tantalum, bismuth trioxide And combinations thereof. Examples thereof include silicon oxide, aluminum oxide, tantalum oxide, and titanium oxide.

In addition, inorganic nitrides such as silicon nitride (Si ₃ N ₄ , Si _x N _y (x, y &gt; 0)) and aluminum nitride can also be suitably used.

Further, the insulator layer may be formed of a precursor containing an alkoxide metal, and the insulator layer is formed by coating a solution of the precursor, for example, on a substrate, and subjecting it to a chemical solution including heat treatment.

As a metal in the said alkoxide metal, it selects from a transition metal, a lanthanoid, or a main group element, for example, Barium (Ba), strontium (Sr), titanium (Ti), bismuth (Bi), tantalum Rum (Ta), zirconium (Zr), iron (Fe), nickel (Ni), manganese (Mn), lead (Pb), lanthanum (La), lithium (Li), sodium (Na), potassium (K), Rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), niobium (Nb), thallium (Tl), mercury (Hg), copper (Cu), Cobalt (Co), rhodium (Rh), scandium (Sc), yttrium (Y), etc. are mentioned. As the alkoxide in the alkoxide metal, for example, alcohols containing methanol, ethanol, propanol, isopropanol, butanol, isobutanol and the like, methoxy ethanol, ethoxy ethanol, propoxy ethanol, butoxy And alkoxy alcohols containing ethanol, pentoxy ethanol, heptoxy ethanol, methoxy propanol, ethoxy propanol, propoxy propanol, butoxy propanol, phenoxy propanol, heptoxy propanol, and the like.

When the insulator layer according to one embodiment is made of the above materials, polarization easily occurs in the insulator layer, and the threshold voltage of the transistor operation can be reduced. In addition, when the insulator layer is formed of silicon nitride such as Si ₃ N ₄ , Si _x N _y , and SiON _x (x, y> 0), the depletion layer is more likely to be generated, and the threshold of the transistor operation is achieved. The voltage can be further reduced.

Examples of the insulator layer using the organic compound include polyimide, polyamide, polyester, polyacrylate, photoradical polymerization system, photocurable resin of photocationic polymerization system, copolymer containing acrylonitrile component, polyvinylphenol, Polyvinyl alcohol, a novolak resin, cyanoethyl pullulan, etc. can also be used.

In addition, wax, polyethylene, polychloropyrene, polyethylene terephthalate, polyoxymethylene, polyvinyl chloride, polyvinylidene fluoride, polymethyl methacrylate, polysulfone, polycarbonate, polyimide cyanoethyl pullulan, poly (Vinylphenol) (PVP), poly (methyl methacrylate) (PMMA), polycarbonate (PC), polystyrene (PS), polyolefin, polyacrylamide, poly (acrylic acid), novolac resin, resol resin, polyimide In addition to polyxylene and epoxy resins, it is also possible to use a polymer material having a high dielectric constant such as pullulan.

An organic compound material and a polymer material used for the insulator layer, which are organic compounds having water repellency, and having water repellency, suppress the interaction between the insulator layer and the organic semiconductor layer, and utilize the cohesiveness originally possessed by the organic semiconductor to The device performance can be improved by increasing the crystallinity of the semiconductor layer.

In addition, when using the top gate structure shown in FIG. 1 and FIG. 4, when such an organic compound is used as a material of an insulator layer, since the damage to an organic semiconductor layer can be made small, it is an effective method.

The insulator layer may be a mixed layer using a plurality of inorganic or organic compound materials as described above, or may be a laminate structure thereof. In this case, the performance of the device may be controlled by mixing or laminating a material having a high dielectric constant and a material having water repellency as necessary.

In addition, the insulator layer may include an anodization film or the anodization film as a configuration. The anodic oxide film is preferably sealed. The anodic oxide film is formed by anodizing a metal capable of anodizing by a known method. Aluminum or tantalum is mentioned as a metal which can be anodized, There is no restriction | limiting in particular in the method of anodizing, A well-known method can be used. An oxide film is formed by performing anodization. As the electrolyte solution used for the anodic oxidation treatment, any one can be used as long as it can form a porous oxide film, and in general, sulfuric acid, phosphoric acid, hydroxide, chromium acid, boric acid, sulfamic acid, benzenesulfonic acid, or the like, or these Mixed acids or salts thereof in combination of more than one kind are used. Anodic oxidation treatment conditions cannot be uniformly specified because they vary depending on the electrolyte solution to be used. Generally, the concentration of the electrolyte solution is 1 to 80 mass%, the temperature of the electrolyte solution is 5 to 70 ° C, and the current density is 0.5 to 60 A / cm 2. A voltage of 1 to 100 volts and an electrolysis time of 10 seconds to 5 minutes are suitable. Preferred anodizing treatment is a method of treating with a direct current using an aqueous solution of sulfuric acid, phosphoric acid or boric acid as the electrolyte, but an alternating current may be used. Examples of the concentration of these acids include 5 to 45% by mass, the temperature of the electrolyte solution is 20 to 50 ° C, the current density is 0.5 to 20A / cm 2, and the electrolytic treatment can be performed for 20 to 250 seconds.

As the thickness of the insulator layer is thin, the effective voltage applied to the organic semiconductor increases, so that the driving voltage and the threshold voltage of the device itself can be reduced, but on the contrary, since the leakage current between the source and the gate increases, It is necessary to select a film thickness, for example, 10 nm-5 micrometers, 50 nm-2 micrometers, or 100 nm-1 micrometer.

Moreover, arbitrary orientation treatment can also be performed between the said insulator layer and a semiconductor layer. An example is a method of improving the crystallinity of an organic semiconductor layer by performing a water repellent treatment or the like on the surface of the insulator layer and reducing the interaction between the insulator layer and the organic semiconductor layer, and a silane coupling agent such as octadecyl trichlorosilane. Examples of a method in which a self-organizing alignment film material such as phosphorus, trichloromethylsilazane, alkane phosphoric acid, alkanesulfonic acid, or alkancarboxylic acid are brought into contact with the surface of the insulating film in a liquid or gaseous state to form a self-organizing film, and then appropriately dried. Can be. Further, a film made of polyimide or the like is provided on the surface of the insulating film so as to be used for the alignment of the liquid crystal, and a method of polishing the surface can also be used.

As the method for forming the insulator layer, a dry process such as vacuum deposition, molecular beam epitaxial growth, ion cluster beam, low energy ion beam, ion plating, CVD, sputtering, atmospheric plasma, or spray coating or spin And wet processes such as coating, blade coating, dip coating, casting, roll coating, bar coating, die coating, coating, and patterning such as printing or ink jet. It can be used depending on the material. The wet process is a method of applying and drying a liquid obtained by dispersing an inorganic oxide fine particle in an arbitrary organic solvent or water using a dispersing aid such as a surfactant as necessary, or applying and drying a solution of an oxide precursor such as an alkoxide body. The so-called sol-gel method is used.

Further, for example, a gas barrier layer may be formed on the entire surface or part of the outer circumferential surface of the transistor element in consideration of the influence on the semiconductor layers such as oxygen and water contained in the atmosphere. As the material for forming the gas barrier layer, those commonly used in this field may be used. For example, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polyvinylidene chloride, polychlorotrifluoroethylene, or the like may be used. Can be mentioned. Moreover, the inorganic substance which has the insulation illustrated by the said insulator layer can also be used.

In the thin film transistor, the light emitting device may be electrically connected to the thin film transistor, and then the light emitting device may be controlled using a current flowing between a source and a drain, and the flat panel display may be configured using the thin film transistor. .

In the above-described thin film transistor, there is provided a thin film light emitting transistor that obtains light emission by using a current flowing between a source and a drain, and controls light emission by applying a voltage to a gate electrode.

The thin film transistor can also be used as a light emitting element by using charges injected from source and drain electrodes. That is, the thin film transistor can be used as a thin film light emitting transistor which also functions as a light emitting element (organic EL element). This can control the light emission intensity by controlling the current flowing between the source and drain electrodes with the gate electrode. Since the transistor and the light emitting element for controlling the light emission can be integrated, the cost can be reduced due to the improvement of the aperture ratio of the display and the simplification of the manufacturing process.

1 to 4 show an example of a thin film transistor according to one embodiment.

5 shows an example of a thin film transistor having a graphene layer and a control layer.

6 shows an example of a thin film transistor including a metal atom layer between the graphene layer and the adjustment layer.

Claims (7)

A thin film transistor having at least three gate electrodes, a source electrode, a drain electrode, an insulator layer, and a semiconductor layer on a substrate, and controlling a current between the source and the drain by applying a voltage to the gate electrode, wherein the semiconductor layer A thin film transistor having a pen layer and a control layer. The method of claim 1, The area of the graphene is a thin film transistor of 1mm ² or more. The method of claim 1, And the control layer is an oxide, nitride, sulfide or a mixture thereof. The method of claim 1, The thin film transistor having a metal atomic layer interposed between the graphene layer and the control layer. The method of claim 4, wherein The metal atom layer is a thin film transistor in which the Al atoms are stacked in a structure of 1 to 3 layers. A thin film transistor having at least three gate electrodes, a source electrode, a drain electrode, an insulator layer, and a semiconductor layer on a substrate, and controlling a current between the source and the drain by applying a voltage to the gate electrode, wherein the semiconductor layer It has a pen layer and an adjustment layer, And emitting light by using a current flowing between the source and the drain, and controlling light emission by applying a voltage to a gate electrode. A thin film transistor having at least three gate electrodes, a source electrode, a drain electrode, an insulator layer, and a semiconductor layer on a substrate, and controlling a current between the source and the drain by applying a voltage to the gate electrode, wherein the semiconductor layer A thin film transistor having a pen layer and a control layer; And And a light emitting device electrically connected to the thin film transistor.

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