CN102842602A

CN102842602A - Amorphous zinc magnesium oxide/carbon nano tube composite thin film transistor and preparation method thereof

Info

Publication number: CN102842602A
Application number: CN2012103683063A
Authority: CN
Inventors: 廖蕾; 刘兴强
Original assignee: Wuhan University WHU
Current assignee: Wuhan University WHU
Priority date: 2012-09-28
Filing date: 2012-09-28
Publication date: 2012-12-26
Anticipated expiration: 2032-09-28
Also published as: CN102842602B

Abstract

The invention relates to a high performance thin film transistor. According to the high performance thin film transistor, an amorphous zinc magnesium oxide/carbon nano tube composite thin film is used as a semiconductor channel layer; and in the composite thin film, the molar ratio of carbon atoms to metal cations in oxide is in the range of 0 to 25 percent. By modulating components in the oxide, the continuous regulation and control on a threshold voltage from minus 10V to 6V are implemented. A preparation method of the high performance thin film transistor comprises the following steps of: compounding a carbon nano tube with zinc magnesium oxide to obtain the amorphous zinc magnesium oxide/carbon nano tube composite thin film; and using the amorphous zinc magnesium oxide/carbon nano tube composite thin film as the semiconductor channel layer and obtaining a high performance transparent composite thin film field effect transistor by a transistor manufacturing process. The preparation method has the advantages of simple process, low requirements on the conditions, high controllable degree and low cost.

Description

Amorphous zinc oxide magnesium/carbon nano-tube coextruded film transistor and preparation method thereof

Technical field

The present invention relates to a kind of amorphous zinc oxide magnesium/carbon nano-tube coextruded film transistor and preparation method thereof, metal nanometer material and field of nanometer devices.

Background technology

Arrival along with the information age; Display device (LCD), Electronic Paper are just being quickened to develop to the direction of panelized, energy-conservationization, are that the active array driving display spare of switch element becomes the outstanding person in numerous flat panel displays with thin-film transistor (TFT) wherein.TFT is a kind of field-effect semiconductor device, comprises several important such as substrate, semiconductor channel layer, insulating barrier, grid and source-drain electrode, and wherein semiconductor channel layer is most important to device performance.

At present, for TFT-LCD, semiconductor channel layer wherein mainly adopt amorphous silicon ( a-Si) and polycrystalline SiTFT ( p-Si). aThe TFT-LCD of-Si system has characteristics such as preparation technology is simple, leakage current is little, becomes a kind of display device that present application is the widest, with fastest developing speed, technology is the most ripe.But along with LCD develops towards high definition and big capacity of display direction, and pixel element size is more and more littler, in order to guarantee sufficiently high aperture opening ratio, requires the size of TFT littler.Simultaneously, because the increase of picture element density, the charging interval of unit pixel is shorter, and the mobility that improves TFT just seems rather important.Yet, aThe mobility of-Si material～1 cm ²/ Vs and doping efficiency are lower, can not satisfy the requirement of small size, high charge ability TFT.In addition a-Si material has very strong photoelectric effect, can reduce the OFF resistance of TFT, influences the charge storage characteristic of liquid crystal pixel.Exactly because aThere are the problems referred to above in-Si thin-film transistor, and the nineties later stage, people arrived diversion p-Si material, this be because pThe carrier mobility ratio of-Si aHigh 1～2 order of magnitude of-Si.This just makes p-Si is that the response speed of TFT is fast, and the view data writing speed is fast.But, at present pThere are two problems in the TFT of-Si system: the one, and the off-state current of TFT is bigger; The 2nd, the low temperature large-area preparation of high mobility polycrystalline silicon material is difficulty.Therefore people seek performance excellent material system more constantly.

Simultaneously, organic EL Display Technique also is current scientific and technological circle and the generally good a kind of up-and-coming Display Technique of industrial circle.But also there is the phenomenon of being blocked by Si-TFT of major part (the 70 %-90 %) light that is sent in Si-TFT-OLED.And the brightness of OLED is directly proportional with its injection current, thus in order to improve its display brightness, need to increase injection current, however the electric current increase can cause heating to increase, and causes component failure to quicken.

As one of TFT material, transparent oxide semiconductor (TCO) receives attracting attention of researcher and display screen production firm.In the amorphous oxide semiconductor of current research; Conduction band mainly is made up of the metal cation long radius s track of spherical symmetric; Adjacent orbit produces bigger overlapping; For the transmission of electronics has formed passage, so just do not receive the influence of non crystalline structure, make the amorphous oxide semiconductor material have bigger carrier mobility.Therefore TCO-TFT with a-Si TFT compares because have that high electron mobility, high electricity are led, low growth temperature and high light transmittance become one of current research focus.For flexible display device, but amorphous state oxidation transparent oxide TFT because have normal temperature growth, film is highly polished, stress is low, compatibility is good and the advantage of large area deposition possibly become the preferred material of the demonstration of flexible flat from now on TFT driving switch array.

Yet the birth of any new technology all needs a process to real practicability, and non-crystal oxide yet faces some problems, such as carrier mobility generally all<10 cm ²/ Vs also has bigger raising space.Again it, the high problem of amorphous oxides thin-film transistor ubiquity threshold voltage of present stage is not suitable for the demand of following low consumption circuit development, presses for it is modulated.

Summary of the invention

It is high that problem to be solved by this invention provides a kind of carrier mobility, high performance thin film transistor that threshold voltage is controlled and preparation method thereof.

In order to address the above problem, high performance thin film transistor provided by the present invention is a semiconductor channel layer with amorphous zinc oxide magnesium/carbon nano-tube coextruded film, and in laminated film, the metal cation mol ratio in carbon atom and the oxide is between 0-25%.Through modulation, realized the continuous regulation and control of threshold voltage from-10V to 6V to oxide component.

The transistorized preparation method of above-mentioned high performance thin film is:

CNT and magnesium zinc are carried out compound, obtain amorphous zinc oxide magnesium/carbon nano-tube coextruded film, and, obtain high-performance transparent composite film field-effect transistor through transistor fabrication as semiconductor channel layer.

Concrete scheme is:

1) be 0.92% to join in the EGME with monoethanolamine/EGME volume ratio at first with stabilizer alcohol amine; Solution is designated as A; Mol ratio 1:5 ~ 10 with Mg:Zn join in the solution A magnesium nitrate and zinc acetate as presoma; The total mol concentration of controlling all metal cations is 0.03 mol/L, and ultrasonic even, gained solution is designated as B;

2) be dispersed in the organic solvent CNT is ultrasonic; And according to the molal weight of carbon and oxide than between 0-25%, the CNT dispersion liquid is joined in the solution B, and continues ultrasonic; CNT is uniformly dispersed, and gained solution is designated as C;

3) solution C being spun in advance growth has on the substrate of insulating barrier, and the spin coating of oven dry continued is until reaching desired thickness;

4) thermal annealing in atmosphere promptly obtains amorphous zinc oxide magnesium/carbon nano-tube coextruded film material;

5) utilize ultraviolet photolithographic technology,, utilize wet etching that laminated film is etched into fritter, then through photo etched mask, Cr/Au electrode vapor deposition for the second time and peel off and to obtain indium zinc oxide/carbon nano-tube coextruded film transistor through the mask first time.

The present invention is a basic material with amorphous metal oxide magnesium zinc film; Compound a spot of metallicity many (list) wall carbon nano tube in the film the inside; Utilize the CNT high carrier mobility, improve firing current, mobility and the mechanical flexibility of amorphous metal oxide film.With this laminated film as semiconductor channel layer; Obtain high-performance amorphous oxides/carbon nano-tube coextruded film field-effect transistor through transistor fabrication; And through accurate control to the channel layer materials component; The regulation and control of threshold voltage have been realized crystal is closed, to satisfy various demands of applications.

By the prepared amorphous oxides/carbon nano-tube coextruded film transistor of the inventive method, carrier mobility is up to 135 cm ²/ Vs, switch current ratio are higher than 10 ⁸, threshold voltage from-10 V to adjustable continuously 2 V.

Preparation method of the present invention directly adopts sol-gal process, but technology is simple, low to requirement for experiment condition, controllable degree is high, large tracts of land with low cost is produced in batches and repeatability is high and meet environmental requirement.

Description of drawings

Fig. 1: (a) transmission electron micrograph of employed CNT in this experiment, illustration is a high resolution picture, engineer's scale is 5 nm; (b) the Raman collection of illustrative plates of laminated film transistor channel layer in this experiment, illustration is the optics picture of thin-film transistor, engineer's scale is 10 μ m.

Carbon atom among Fig. 2: the embodiment 2 and metal cation ratio are 0 and 12.5% the transistorized electric property curve of laminated film.Wherein (a) and (b) be respectively the transistorized transfer curve of ZnMgO base film, (b) be respectively (d) that the ZnMgO base film is transistorized to be its curve of output.

Fig. 3: (a) the transistorized transfer curve of ZnMgO/CNTs laminated film of different Mg and Zn ion mol ratio among the embodiment 3; (b) among the embodiment 4 the transistorized mobility of ZnMgO/CNTs laminated film of different Mg and Zn ion mol ratio and threshold voltage along with the change curve of Mg and Zn different mol ratio example; This shows; For the ZnMgO/CNTs laminated film, can recently realize the transformation of ZnMgO/CNTs laminated film transistor from the depletion type to enhancement mode through modulation Mg and Zn mole fully.

Embodiment

Embodiment 1:

(1) 0.293 g Zinc diacetate dihydrate and 0.043 g magnesium nitrate hexahydrate are dissolved in the EGME of 50 mL, and add 0.46 mL monoethanolamine, be designated as solution D as stabilizer ₁, stir 2 h, growth in advance there is the thick SiO of 100 nm ₂The highly doped Si sheet of insulating barrier carries out ultrasonic cleaning; Utilize spin coater to carry out spin coating with the rotating speed of 3000 rpm; Then in atmosphere 150 ℃ the baking 10 min after; Spin coating one deck again on the basis of last layer obtains the thick laminated film of 60 nm, and 350 ℃ of thermal annealing 40 min obtain composite film material in atmosphere at last; (2) utilize the ultraviolet photolithographic technology; Through the mask first time; After utilizing wet etching (watery hydrochloric acid of 10 wt%) 2 min divided thin film is slit into the fritter that the area size is 1 mm * 1 mm, to reduce introducing parasitic capacitance and leakage current in the transistor preparation process.Then through photo etched mask for the second time, utilize prepared by heat evaporation Cr/Au electrode and peel off and can obtain the ZnO film field-effect transistor.

The electric property curve of the prepared thin-film transistor that goes out sees that accompanying drawing 2 (a) and (c), Fig. 1 (a) are the transmission electron microscope image of the CNT that uses in this experiment, and illustration is its high resolution transmission electron microscope figure, and engineer's scale is 5 nm; Fig. 1 (b) is the optical microscope photograph of thin-film transistor for the Raman collection of illustrative plates of the transistorized channel layer of laminated film in this experiment, illustration, and engineer's scale is 20 microns.

Embodiment 2:

(1) with 9 mg CNT (CNT) ultrasonic dissolutions in the EGME of 100 mL, it is for use as mother liquor that ultrasonic 4 h evenly suspend it, is designated as solution A ₁0.293 g Zinc diacetate dihydrate and 0.043 g magnesium nitrate hexahydrate are dissolved in the solution A of 50 mL, and add 0.46 mL monoethanolamine, be designated as solution D as stabilizer ₂, stir 2 h; Add 50 mL solution A again ₁, continue ultrasonic 1 h then to obtain the precursor liquid of uniform laminated film.Growth in advance there is the thick SiO of 100 nm ₂The highly doped Si sheet of insulating barrier carries out ultrasonic cleaning; Utilize spin coater to carry out spin coating then with the rotating speed of 3000 rpm; Then in atmosphere 150 ℃ the baking 10 min after; Spin coating one deck again on the basis of last layer obtains the thick laminated film of 60 nm, and 350 ℃ of thermal annealing 40 min obtain composite film material in atmosphere at last; (2) utilize the ultraviolet photolithographic technology; Through the mask first time; After utilizing wet etching (watery hydrochloric acid of 10 wt%) 2 min divided thin film is slit into the fritter that the area size is 1 mm * 1 mm, to reduce introducing parasitic capacitance and leakage current in the transistor preparation process.Then through photo etched mask for the second time, utilize prepared by heat evaporation Cr/Au electrode and peel off and can obtain the ZnMgO TFT.

The mol ratio of metal cation is that 12.5% the transistorized electrology characteristic curve of amorphous metal oxide/carbon nano-tube coextruded film is seen Fig. 2 (b) and (d) in carbon atom and the laminated film.

Embodiment 3:

(1) with 9 mg CNT (CNT) ultrasonic dissolutions in the EGME of 100 mL, it is for use as mother liquor that ultrasonic 4 h evenly suspend it, is designated as solution A ₃Zinc diacetate dihydrate and the 0.064 g magnesium nitrate hexahydrate of 0.275 g are dissolved in the EGME of 25 mL, and add 0.46 mL monoethanolamine, be designated as solution D as stabilizer ₃0.293 g, four nitric hydrate indiums, 0.043 g, four nitric hydrate magnesium are dissolved in the EGME of 25 mL, and add 0.46 mL monoethanolamine, be designated as solution D as stabilizer ₄0.3 g Zinc diacetate dihydrate and 0.035 g magnesium nitrate are dissolved in the EGME of 25 mL, and add 0.46 mL monoethanolamine, be designated as solution D as stabilizer ₅, with above-mentioned solution D ₃, D ₄, D ₅All stir 2 h; All add the finely dispersed solution A of 25 mL then ₃, continue ultrasonic 1 h to obtain the precursor liquid of uniform laminated film.Growth in advance there is the thick SiO of 100 nm ₂The highly doped Si sheet of insulating barrier carries out ultrasonic cleaning; Utilize spin coater to carry out spin coating then with the rotating speed of 3000 rpm; Then in atmosphere 150 ℃ the baking 10 min after; Spin coating one deck again on the basis of last layer obtains the thick laminated film of 60 nm, and 350 ℃ of thermal annealing 40 min obtain composite film material in atmosphere at last; (2) utilize the ultraviolet photolithographic technology; Through the mask first time; After utilizing wet etching (watery hydrochloric acid of 10 wt%) 2 min divided thin film is slit into the fritter that the area size is 1 mm * 1 mm, to reduce introducing parasitic capacitance and leakage current in the transistor preparation process.Then through photo etched mask for the second time, utilize prepared by heat evaporation Cr/Au electrode and peel off and can obtain the ZnO film field-effect transistor.

In laminated film, the mol ratio of metal cation is 25% in carbon atom and the laminated film, and the mol ratio of Mg and Zn is respectively 1/5,1/8,1/10; The transistorized electrology characteristic curve of laminated film is seen Fig. 3 (a), and Fig. 3 (b) is the relation curve of mol ratio of a series of concrete performance parameter and the Mg and the Zn of thin-film transistor.

Claims

1. amorphous zinc oxide magnesium/carbon nano-tube coextruded film transistor is characterized in that, is semiconductor channel layer with various oxide/carbon nano-tube coextruded films, and in laminated film, the metal cation mol ratio in carbon atom and the oxide is between 0-25%.

2. the transistorized preparation method of the described laminated film of claim 1 is characterized in that, in turn includes the following steps:

2) be dispersed in the organic solvent CNT is ultrasonic, and according to the molal weight of carbon and oxide than between 0-25%, the CNT dispersion liquid is joined in the solution B, and continues ultrasonicly, CNT is uniformly dispersed, gained solution is designated as C;