WO2013159150A1 - Solution-processed low temperature amorphous thin films - Google Patents

Solution-processed low temperature amorphous thin films Download PDF

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WO2013159150A1
WO2013159150A1 PCT/AU2013/000428 AU2013000428W WO2013159150A1 WO 2013159150 A1 WO2013159150 A1 WO 2013159150A1 AU 2013000428 W AU2013000428 W AU 2013000428W WO 2013159150 A1 WO2013159150 A1 WO 2013159150A1
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thin film
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annealing
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Birendra SINGH
Jacek Jasieniak
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Commonwealth Scientific And Industrial Research Organisation
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    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104Forming layers
    • H01L21/02365Forming inorganic semiconducting materials on a substrate
    • H01L21/02367Substrates
    • H01L21/0237Materials
    • H01L21/02373Group 14 semiconducting materials
    • H01L21/02381Silicon, silicon germanium, germanium
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    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104Forming layers
    • H01L21/02365Forming inorganic semiconducting materials on a substrate
    • H01L21/02436Intermediate layers between substrates and deposited layers
    • H01L21/02439Materials
    • H01L21/02488Insulating materials
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    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104Forming layers
    • H01L21/02365Forming inorganic semiconducting materials on a substrate
    • H01L21/02518Deposited layers
    • H01L21/02521Materials
    • H01L21/02551Group 12/16 materials
    • H01L21/02554Oxides
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    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
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    • H01L21/02365Forming inorganic semiconducting materials on a substrate
    • H01L21/02518Deposited layers
    • H01L21/02521Materials
    • H01L21/02565Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
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    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104Forming layers
    • H01L21/02365Forming inorganic semiconducting materials on a substrate
    • H01L21/02518Deposited layers
    • H01L21/02587Structure
    • H01L21/0259Microstructure
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    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
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    • H01L21/02365Forming inorganic semiconducting materials on a substrate
    • H01L21/02612Formation types
    • H01L21/02617Deposition types
    • H01L21/02623Liquid deposition
    • H01L21/02628Liquid deposition using solutions
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    • H01L29/00Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof; Multistep manufacturing processes therefor
    • H01L29/66Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/66007Multistep manufacturing processes
    • H01L29/66969Multistep manufacturing processes of devices having semiconductor bodies not comprising group 14 or group 13/15 materials
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    • H01L29/00Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof; Multistep manufacturing processes therefor
    • H01L29/66Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76Unipolar devices, e.g. field effect transistors
    • H01L29/772Field effect transistors
    • H01L29/78Field effect transistors with field effect produced by an insulated gate
    • H01L29/786Thin film transistors, i.e. transistors with a channel being at least partly a thin film
    • H01L29/7869Thin film transistors, i.e. transistors with a channel being at least partly a thin film having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
    • H01L29/78693Thin film transistors, i.e. transistors with a channel being at least partly a thin film having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate the semiconducting oxide being amorphous

Abstract

A method of preparing an amorphous metal oxide thin film. The method includes providing a fluid medium including an inorganic material dispersed in a solvent, providing a substrate, contacting the fluid medium with the substrate to produce a thin film on the substrate, and annealing the thin film. The inorganic material is a non-halide containing metal salt. The method further includes subjecting the thin film to an oxidative treatment to release volatile organic components from the thin film, prior to the annealing step. A thin film transistor produced by the method is also described.

Description

Solution-processed low temperature amorphous thin films

Field of the invention

The invention relates to a process for producing low-temperature amorphous0 metal oxide thin films for electronic applications. Background of the invention

Current flat panel displays employ amorphous hydrogenated silicon (a-Si:H) transistors to turn on and off individual light emitting pixels. Despite a-Si:H transistors being widely adopted in today's technologies, they are deposited at 350°C using plasma enhanced chemical vapour deposition, have many problems related to instability under illumination and electrical bias, and possess a low charge mobility (<1 cmW1 ). Each of these factors highlight material and deposition restrictions that need to be overcome to meet the growing demands of future light display requirements.

Poly-crystalline Si transistors are an alternate technology that are also widely utilized in devices due to their advantageously high charge carrier mobility (>100 cmV V1). However, one of the major drawbacks of poly-crystalline Si transistors is their electrically unacceptable variation of electrical properties due to grain boundary problems (short range uniformity). Because of this drawback, the resulting transistors cannot drive large displays (e.g. 55 inches) that operate at frame rates greater than 120 Hz. Hence, in addition to high mobility, electrically stable materials are required for developing displays with higher resolution, a faster frame rate and a larger pixel size.

Recent material advances have shown that transistors based on amorphous metal oxides may provide the necessary mobilities and electrical stability to be useful in future display technologies. From an electrical viewpoint, such amorphous oxides are relatively insensitive to the presence of structural disorder, which permits high charge carrier mobilities and electrically stability to be achievable. This ensures that the major requirements that amorphous metal oxides need to meet for light emitting applications is that the transistors can be deposited on a variety of substrates sizes and compositions, apd that the processing temperature is as low as possible. The most conventional method for depositing amorphous metal oxide transistors to date has been sputtering. This process can meet most of the necessary requirements for display technologies, but it is slow and equipment intensive, and lacks the scalability that is necessary to fabricate large displays (60inches or above). Recently, solution processing schemes with high throughput have been developed, but these require a high annealing temperature (>400°C).

The present invention^ seeks to alleviate at least some of the above mentioned disadvantages by providing a process for the fabrication of low-temperature solution processed amorphous metal oxides. Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art. Summary of the invention

The invention is partly based on the observation that an oxidative treatment of solution deposited metal oxide precursor films prior to thermal treatment is found to drastically improve the electronic properties of the resulting amorphous metal oxide thin- films. In a first aspect, the invention provides a method of preparing an amorphous metal oxide thin film, the method including providing a fluid medium including an inorganic material dispersed in a solvent, providing a substrate, contacting the fluid medium with the substrate to produce a thin film on the substrate, and annealing the thin film. The inorganic material is a non-halide containing metal salt. The method further includes subjecting the thin film to an oxidative treatment to release volatile organic components from the thin film, prior to the annealing step.

Preferably the step of subjecting the thin film to an oxidative treatment includes exposing the thin film to an environment including one of H20, O2, 02 plasma, 03, plasma 03, ultraviolet 03, N20 and plasma N20. Most preferably the oxidative treatment is provided by ultraviolet 03 (UV ozone). Advantageously, the intensity of the UV ozone with wavelength 185nm is 300W/cm2.

The inorganic material is preferably selected from metal carboxylates, alkoxides, diones, cubanes, amides, nitrates, sulfates, hydroxides, tri-thiocarbamates, xanthates, carbamates, and carbonyls. Preferably the metal salt is one of, or a mixture of, Gallium, Indium, Zinc or Tin metal centre with an alkoxide, carboxylate or dione stabilizer, and the solvent is one of water, alcohols, aminoalcohols, carboxylic acids, ethers, hydroxyesters, aminoesters, amides, sulfoxides and mixtures thereof

The method of the invention may further include adding an additive component to the fluid medium to induce changes in one or more of metal coordination, redox states, solubility, thermal stability, and chemical reactivity. The additive may be selected from the group including alanine, ammonia, aniline, imidazole, pyridine, pyrimidine, pyrazine, piperidine, piperazine, quinoline, 1 ,3 thiazole, nitrates, imides, amides, primary amines, secondary amines and tertiary amines of an linear alkyl, branched alkyl, aromatic, carboxylate, alcoholic, carboxylic, ester, ether, diamines and or mixtures thereof, water, linear and branches alkyl carboxylates, linear and branches alcohols, esters, ethers, and beta-diketones.

In a preferred embodiment the fluid medium is deposited on the substrate component by spin-coating, ink-jet printing, spray coating, gravure printing, or slot-die coating.

Preferably the thin film prepared by the method of the invention has a thickness less than 100nm, more preferably less than 50nm, and more preferably in the range 10- 30nm.

The step of oxidising the thin film is preferably performed at a substrate temperature between room-temperature and 150°C.

The step of annealing the thin film is preferably conducted at a temperature between 200°C and 400°C, and preferably in air with a controlled level of humidity (0- 100%), oxygen, nitrogen with a controlled level of humidity (0- 100%), argon with a controlled level of humidity (0- 100%), or a vacuum environment. Advantageously, the step of annealing is performed by a radiative heat source, a laser, a pulsed flash of light or other suitable means, and is preferably performed for less than 1 hour.

The invention also extends to a thin film transistor device produced by the method. The method of the invention is also suitable for use in flexible substrates such as display units having a curved surface (for example in semitransparent displays/circuits). Advantageously, the process can be used on any mechanically stable, flexible transparent. or semi-transparent substrate. Preferably, flexible polymers of 100-200 mm in thickness, having a glass transition temperature of up to 300°C (for example, Aralyte™) or metal foils are more suitable.

Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

Brief description of the drawings

The invention will now be described by way of example, with reference to the accompanying Figures, in which:

Figure 1 shows GA-FTIR for IZO thin-films annealed at different temperatures under an ambient environment that were prepared from chloride precursors as per Example 1 both without (A) and with (B) pre-thermal treatment UV-Ozone treatment. Figure 2 shows high resolution O 1s spectra for the IZO samples prepared according to Example 1 using (A) chloride salts with no UV-ozone treatment and (B) chloride salt with UV-ozone treatment.

Figure 3 shows GA-FTIR for IZO thin-films annealed at different temperatures under an ambient environment that were prepared from acetylacetone precursors as per Example 2 both without (A) and with (B) pre-thermal treatment UV-Ozone treatment.

Figure 4 shows high resolution O 1s spectra for the IZO samples prepared according to Example 2 using (A) ACAC salts with no UV-ozone treatment and (B) ACAC salts with UV-ozone treatment. Figure 5 compares field effect mobility for IZO thin film transistors with and without UV-ozone treatment. Upper panel: For thin films prepared with ACAC solution as per Example 2; lower panel: thin films prepared with chloride solutions as per Example 1. Figure 6 shows a comparison of the device parameters of thin film transistors prepared with IZO thin films according to Example 2 with and without UV-ozone treatment. Upper panel: Threshold voltage; lower panel: on/off ratio.

Figure 7 shows a comparison of bottom contact thin film transistors transfer characteristics with and without UV-ozone treatment for devices with identical mobility. Large negative threshold voltage shift is observed for non UV-ozone treated films.

Figure 8 shows the relative field effect mobility vs. UV-Ozone exposure time during which substrates were held at 150°C. Subsequently all the films are thermally annealed at 300°C.

Figure 9 shows the relative field effect mobility vs. thermal annealing time at constant 300°C. Prior to this experiment, all the films were UV-ozone treated for 60 minutes at 150°C.

Figure 10 shows the transfer characteristics of top contact thin film transistors with films UV-ozone treated and subsequently thermally annealed at 300°C. The devices were Au source drain contact channel width of 45 μΐη and channel length of 151 μπ\ giving W/L=0.3. From the respective slopes, 6 D 5VG, device parameters: L, W, capacitance per unit area, C, of 10 nF/cm2, the field effect mobility^2w) ~ 35 cm /Vs was calculated using' 21 ( δ4*ρ

Hl" WC, 5VG

Figure 1 displays the output characteristics of thin film transistors characteristics shown in Figure 10. Figure 12 shows the plots of the ratio between channel length/channel width versus mobility. The smallest ratio of W/L is found to give the highest mobility due to the interplay between contact resistance and channel resistance. Figure 13 shows (a) Snapshot of the device for the measurement of channel conductivity as a function of applied gate voltage. Devices were with bottom Au source drain contact channel width of 1503.5 μητι and channel length of 27.2 μιη giving W/L=55.

(b) Plot of ratio of channel conductivity as a function of applied gate voltage for thin films with UV-ozone treated and subsequently thermally annealed at 300°C. Intrinsic mobility (μ4νν) ~ 31.54 cm2/Vs is derived from the slope of the curve (1.9 x 10"4 S.V/m) using equation:

Figure imgf000008_0001
where D is the distance between the voltage probes, W is the channel width, C, is the capacitance of the gate dielectric, and d is the derivative operator. From the same device, when characterised as bottom contact transistor, respective slopes, 5 /D/6VG. device parameters: L, W, capacitance per unit area, of 10 nF/cm2, the field effect
Figure imgf000008_0002
~ 1 cm2/Vs was calculated using:
Figure imgf000008_0003

Figure 14 shows the evolution of the transfer curves for top contact thin film transistor with L= 60 μηη, W= 2000 μιτι, with films UV-ozone treated and subsequently thermally annealed at 300eC. The device was stressed under the following conditions: the drain current was set to 10 μΑ and the drain voltage was fixed at 20 V. The maximum stress duration was 36 000s.

Figure 15 shows the variation in the mobility (μ2νν) and threshold voltage shift as function of stress time.

Figure 16 shows (a) Circuitry of the unipolar "standard logic" inverter (b) output curves of an inverter.

Figure 17 shows frequency characteristics of a discrete transistor.

Figure 18 shows plot of /C2 for 1 kHz and 5 kHz, voltage going from -0.5V to 1.0V. The dopant densities were 1.13*1015/cm3 and 1.46*1015 /cm3 for measurement at 1 kHz and 5 kHz respectively. Figure 19 shows transfer characteristics of bottom contact thin film transistors with films UV-ozone treated and subsequently thermally annealed at 300°C. The devices were Au source drain contact channel width of 2000 μηη and channel length of 10 μιτι giving W/L=200. (b) Output charactenstics of thin film transistors characteristics shown in Figure 20(a). (c) Plot of ratio of channel length/channel width versus mobility.

Figure 20 shows (a) the out characteristics of a low voltage transistor fabricated using 8 nrri ultra-thin Alumina dielectrics grown by Atomic Layer Deposition instead of S1O2 (b) transfer characteristics of the low voltage transistors operating with 1 V. W/L of the transistor is 2000μηι/60μΐτι. Detailed description of the embodiments

In accordance with preferred embodiments of the invention metal precursor solutions are firstly prepared by combining the metal precursors in an appropriate solvent with any additional additives under air or nitrogen environments. The mixtures are stirred at temperatures which range from room temperature up to 00°C. Following an appropriate reaction time, the precursor solutions are cooled to room-temperature and filtered. The precursor solutions are then deposited by techniques such as spin- coating, ink-jet printing, spray-coating, gravure printing and slot-die coating to give films of thickness up to 100nm.

The precursor solutions can be made of any inorganic material and may be elemental, compound or composite-based. Examples of precursor include, but are not limited to metal carboxylates, alkoxides, diones, cubanes, amides, nitrates, sulfates, hydroxides, tri-thiocarbamates, xanthates, carbamates, and carbonyls. The precursors are dispersed in a solvent, which may simply act to solubilise the species in solution (e.g. benzene), participate in coordinating the metallic centres (e.g. DMSO) or may in fact chemically interact with the metal precursors through reduction or oxidation of the metal species or their stabilizers (e.g. methoxyethanol). The solvent can be water, alcohols, ar inoalcohols, carboxylic acids, ethers, hydroxyesters, aminoesters, amides, sulfoxides and mixtures thereof.

If necessary appropriate additives may also be added to the precursor solutions to induce changes in metal coordination, redox states, solubility, thermal stability, and chemical reactivity. The form of the additives which are added to the precursor solutions vary, but in each case they meet the requirement that they permit for an increased charge mobility at a given thermal annealing temperature following the oxidising step described further below. Examples of appropriate additives of a nitrogen base include alanine, ammonia, aniline, imidazole, pyridine, pyrimidine, pyrazine, piperidine, piperazine, quinoline, 1 ,3 thiazole, nitrates, imides, amides, primary amines, secondary amines and tertiary amines of an linear alkyl, branched alkyl, aromatic, carboxylate, alcoholic, carboxylic, ester, ether, diamines and or mixtures thereof. Other additives include but are not limited to water, linear and branches alkyl carboxylates, linear and branches alcohols, esters, ethers, and beta-diketones.

The as deposited thin films are then treated under an oxidizing environment at a substrate temperature that ranges from room-temperature to 500°C. The oxidizing environment can be composed of hfeO, 02, 02 plasma, 03, plasma O3, ultraviolet 03, N20 and plasma N20. In a preferred embodiment the oxidising environment is ultraviolet 03 (UV ozone). The oxidizing step causes oxidative reactions with the metal passivants in the films to release volatile components (e.g. CO, CO2, COH2, NO, N02l). This reduction in the residual impurities in the films, defined as those species that are not metal or lattice oxygen, occurs only within close proximity to the surface (typically the first 10 to 20nm). Therefore, this oxidizing treatment step is specific to thin-films of less than 50nm, and becomes more effective for even thinner films.

Following the oxidizing treatment, the samples are thermally annealed, under an ambient air, dry air, oxygen, nitrogen, argon, or vacuum environment. The choice of, and use of non-halide containing metal salts greatly reduces the temperature for annealing/sintering. This allows the annealing to be carried out by a radiative heat source, a laser, a pulsed flash of light or other means known to those skilled in the art under milder conditions than what would be necessary for bulk materials. The thermal treatment can be optimally carried out in the presence of specific gases including oxygen, hydrogen, nitrogen, argon, fluoroform etc. The combined oxidizing and thermal steps act to greatly enhance the achievable electronic properties of solution deposited amorphous metal oxide films, particularly at lower temperatures (<400°C) then if thermal treatment was conducted without any pre-oxidizing step. Example 1

Indium Chloride (>99.999%, Sigma-Aldrich), Zinc Chloride (99.999%, Sigma- Aldrich), 2-methoxy ethanol (99% Sigma-Aldrich) and ethanolamine (99%, Sigma- Aldrich) were used as received without further purification. Metal oxide solutions were made in a two-step process: (i) a 0.4 mM solution of Indium Chloride and Zinc Chloride was made in 2-methoxy ethanol with an ln:Zn ratio of 2.3:1. The equivalent of 2:1 ethanolamine:total metal was added as a chelating agent for the metals salts to these solutions. The solution was stirred at 60 °C for 1 hour under ambient conditions before being cooled to room temperature. This solution could be diluted by an appropriate amount of 2-methoxyethanol to achieve the desired concentration of metal species in solution.

To achieve films thicknesses of 15nm when deposited onto UV-Ozone treated silicon dioxide, the indium zinc oxide (IZO) sol-solution was diluted by 2 ml_ of 2- methoxyethanol and spin coated on the silicon dioxide at 2000 RPM for 60 sec at an acceleration of 6000 RPM. The resulting films could be either directly treated thermally or exposed to UV-Ozone treatment prior to being treated thermally. UV-Ozone treatment was carried out for a specific amount of time, which typically ranged from 5-60 minutes. In both cases, the film thickness for temperatures above 200 °C was 15-20nm.

Effect of Oxidative Treatment To demonstrate the effect of UV-Ozone on halide based sol-gel metal oxide thin films, ~20-30 nm thick IZO thin films were deposited on polished silicon substrates with only a natural silicon oxide. The samples were then either exposed to UV-Ozone treatment for 1 hour at 50 °C or left untreated before being thermally annealed for 1 hour under an ambient environment at temperatures between 100 °C and 400 °C. The samples were characterized using Grazing Angle Attenuated Total Reflectance (GATR) FTIR as shown in Figure 1.

Halogeno metal complexes exert stretching bands in the low wavenumber spectral region (<750 cm"1) and thus cannot be detected in the current experimental setup. Despite this, a number of absorption bands were observed within experimental range here (800 - 4000 cm*1). Notably, the halogeno zinc and indium complexes showed signatures of hydration, with broad bands being observed between 2700 cm'1 and 3600 cm"1. Definite signatures of these contributions and that stemming from ethanolamine are observed.

Two minor aliphatic peaks stemming from asymmetric and symmetric CH2 vibrations are observed at 2922 cm"1 and 2857 cm'1, respectively. No definitive CH3 vibrations could be resolved. In the lower wavenumber region four main bands centred at 1605 cm"1, 1490 cm"1, 1063 cm"1 and 1001 cm"1 were observed. Minor contributions are also observed at 1456 cm"1, 1371 cm"1, 1322 cm"1, 1264 cm"1 and 1110 cm"1. The presence of water in the sample can in part explain the existence of the 1605 cm"1 band. In addition an underlying contribution from the N-H stretch is expected within this spectral region. The existence of amines is further confirmed by the presence of the peak at 1001 cm'1, which is believed to originate from the C-N stretching. The strong band at 1490 cm'1 and a weaker should at 1456 cm"1 are assigned to asymmetric and symmetric stretching modes of CH2, both of which exist within the 2-methoxyethanol and the ethanolamine. Consistent with assignment, the minor bands which are observed between 1200 cm"1 and 1400 cm"1 originate from the twisting and wagging of CH2. The minor peak at 1100 cm"1 is tentatively assigned to the metal hydroxide contributions (Shirtcliffe 2003). Finally, the strong band at 1063 cm"1 is expected from contributions of C-O-C, C-O(H) and/or C-C, all potentially stemming from the 2- methoxyethanol species (Coates 2000, Yoshida 1993)

Increasing temperature to 200 °C causes the removal of the majority of the amines from the film and greatly reduces the presence of the 2-methoxyethanol. The water content is also found to drastically decrease following this step. Progressive heating to higher temperatures causes many of these residual organics to be removed. UV-Ozone treatment of the chloride based thin films causes a significant reduction to the ethanolamine and the 2-methoxyethanol content in the film. The strong water peak at ~ 1600 cm"1 does indicate that the film retains moisture. It is likely that the water adsorption has occurred post treatment, due in part to the strong tendency of metal halides to hydrogen bond with water. The 1425 cm"1 is at present unidentified, but its origin is thought to arise from the UV-Ozone treatment. Increasing the annealing temperatures causes the band at 1425 cm"1 to diminish in strength, until it becomes negligible following 400 °C annealing. The evolution of a broad band between 1000- 1100 cm"1 up to a temperature of 250 °C is observed, after which its contribution diminished. This band can be assigned to the formation of metallic O2 adducts (Zehe 1979). Overall, the FTIR of the halide based films with and without UV-Ozone confirms that both the ethanolamine and the 2-methoxyethanol are coordinating the metal salts. The species are removed at increased annealing temperatures, with UV-Ozone acting to remove a substantial quantity of these stabilizers, but leaving visible residue that is retained up to 400 °C. X-ray photoelectron spectroscopy (XPS) was performed on IZO thin-films using halide precursors with and without UV-ozone treatment, then an additional thermal annealing step at different temperatures in air. A complete list of samples are provided in Table 1. XPS was utilized to map out the high resolution O 1s spectra to reveal the nature of the bonding within the first 10 nm of the surface. Table 1. List of IZO thin-films prepared according to Example 1 using chloride precursors and the thermal and oxidative conditions employed for their study through XPS.

Figure imgf000013_0001

Inspection of the high resolution O 1s spectra gives direct evidence of the types of bonding associated with the oxygen existing within the films. Specifically, theoretical and experimental studies of ZnO have revealed that the O 1s contribution of Zn-OH and bulk Zn-0 bonds are split by approximately 1.5-2.0 eV, with the Zn-OH being observed at a binding energy of ~531.2-532 eV and the bulk ZnO being observed at 529.3 eV - 530.6 eV. To determine the nature of the bonding in the systems, Figures 2A and 2B show the high resolution O 1s spectra of the IZO films prepared using chloride precursors without and with pre-thermal treatment UV-Ozone treatment, respectively. Analysis of sample 1 indicates that the oxygen peak is split into two contributions, one being that of the Zn-OH and the other at a slight lower binding energy (~ 1 eV). Work done on oxo compounds such as Zn40(acetate)6 indicates that the destabilization of the central O which is shared among four Zn cations compared to the oxygens of the bridging acetate groups causes shift of the core level binding energy to 531 eV compared to 532.8 eV. The observation of the 531 eV O 1s core level binding energy suggests that clusters may be present within the solutions and consequently the resulting film. Annealing at 200 °C causes a drastic reduction in the core-binding energy and a concordant increase in the hydroxylated Zn species. Increasing the annealing temperature further causes a decrease in the level of hydroxylation and a concordant increase in the bulk ZnO contribution at 530.5 eV.

UV-Ozone treatment of the chlorinated thin-films causes significant hydroxylation of the Zn cation. This is indicated by the pronounced core-level binding contribution at 532 eV. With increasing annealing temperature, the contribution of this species gradually decreases, whilst a concordant increase in the relative contribution of the bulk metal oxide peak is observed. This trend is indicative of the fact that condensation in these systems is occurring with a much greater likelihood than in the non UV-Ozone treated sample, despite the high residual organic content.

Example 2

Indium acetylacetonate (99.99%, Sigma-Aldrich), zinc acetylacetonate hydrate (99.995%, Sigma-Aldrich), 2-methoxy ethanol (99% Sigma-Aldrich) and ethanolamine (99%, Sigma-Aldrich) were used as received without further purification. Metal oxide solutions were made in a two-step process: (i) a 0.4 mM solution of indium acetylacetonate and zinc acetylacetonate was made in 2-methoxyethanoI with an ln:Zn ratio of 2.3:1. The equivalent of 2:1 ethanolamine:total metal was a chelating agent for the metals salts to these solutions. The solution was stirred at 60 °C for 1 hour under ambient conditions before being cooled to room temperature. This solution could be diluted by an appropriate amount of 2-methoxyethanol to achieve the desired concentration of metal species in solution.

To achieve films thicknesses of 15nm when deposited onto UV-Ozone treated silicon dioxide, the indium zinc oxide (IZO) sol-solution was diluted by 2 mL of 2- methoxyethanol and spin coated on the silicon dioxide at 2000 RPM for 60 sec at an acceleration of 6000 RPM. The resulting films could be either directly treated thermally or exposed to UV-Ozone treatment prior to being treated thermally. UV-Ozone treatment was carried out for a specific amount of time, which typically ranged from 5 0 minutes. In both cases, the film thickness for temperatures above 200 °C was 15-20nm.

Effect of Oxidative Treatment

To demonstrate the effect of UV-Ozone on acetylacetonate based sol-gel metal oxide thin films, ~20-30 nm thick IZO thin films were deposited according to Example 3 on polished silicon substrates with only a natural silicon oxide. The samples were then either exposed to UV-Ozone treatment for 1 hour at 50 °C or left untreated before being thermally annealed for 1 hour under an ambient environment at temperatures between 100 °C and 400 °C. GATR-FTIR measurements were then performed on these samples, with the results shown in Figure 3.

Unlike for Si-O, the spectral range to observe excitation of Zn-0 and ln-0 phonon lines occurs at < 650 cm"1, which was not observed by the restricted spectral range of the measurements (menon20 1). Therefore, through this GATR FTIR analysis the organic species which compose the IZO films with and without UV-Ozone treatment at the different annealing temperatures are directly probed. Notably, the underlying contribution of silicon in all samples is evident due to the < 30nm thick IZO films which were studied here.

Figure 3A shows the effect of temperature on IZO samples that were not exposed to UV-Ozone treatment. IZO films annealed at 100 °C show characteristics vibrations of hydrogen bonded hydroxyl groups and N-H functionalities in the 3000 - 3600 cm"1 (Coates 2000). In addition, aliphatic contributions are observed between 2800 - 3000 cm"1. At lower wavenumbers, a strongly absorbing resonance at -1603 cm" 1 is indicative of the N-H bend with the possibility of a broad underlying band from hydrogen bonded water (Coates 2000). As additional confirmation of the presence of amines originating from the complexing ethanoamine ligands, the distinct peak at 1027 cm"1 can be assigned to the C-N vibration (Tseng 2010). The existence of the acetylacetonate coordinating to the Zn cation is observed through the existence of the bands at 1575 cm"1, 1518 cm"1, 1437 cm'1, 1408 cm"1 and 1372 cm'1, which are assigned to the C=0 stretching, C=C-C stretching, Chfe wagging, CH3 asymmetric bending and CH3 symmetric bending, respectively (Nakamoto). Furthermore, the peak at 1306 cm"1 is tentatively assigned to the O-H bending mode of residual 2- methoxyethanol of the ethanolamine (Coates 2000). Finally, the 1069 cm"1 peak is expected from contributions of C-O-C, C-O(H) and C-C, all potentially stemming from either the 2-methoxyethanol or the acetylacetonate species (Coates 2000, Yoshida 1993).

Increasing the annealing temperature to 200 °C causes the absorption bands associated with amines and the 2-methoxyethanol to be significantly reduced. This is consistent with the boiling points of each of these species (ethanolamine Tb= 170 °C and 2-methoxyethanol T = 125 °C). The characteristic C=C-C stretching peak at 1518 cm"1 is also no longer observed at this temperature. Consistent with thermogravimetric analysis, this indicates that the acetylacetonate begins decomposition at this temperature. Notably, this decomposition causes a concordant broadening of the band of peaks between 1530 - 1700 cm"1. This spectral region is characteristic of C=0 functional groups. Thus, a multistep decomposition process that retains C=0 within the films is expected. Ismail studied the thermal decomposition reactions of zinc acetylacetonate hydrate under dry nitrogen (Ismail 1991). Under these conditions, the decomposition mechanism was a complex multi-step process. At 200 °C it was found that decomposition occurred through propyne release and the formation of zinc acetate. The broadening of the peaks within the 1530 - 1700 cm"1 spectral region is consistent with this mechanism. Residual aliphatic contributions in the 1320-1500 cm"1 and 2800 - 3000 cm"1 spectral regions indicate that aliphatic impurities still reside in the film. Increasing the annealing temperature further, causes a gradual reduction in all of the above mentioned absorption bands. Whilst a significant reduction in the intensity of these bands is observed between 200 °C and 250 °C, it is not until 400 °C when the FTIR spectra indicate trace amounts of impurities in the sample, analogous to the original silicon substrates. The hydrogen bonded hydroxyl and/or water content in the films increase up to a temperature of 250 °C, before gradually decreasing. Unlike for the UV-Ozone treated sample, a definitive metal hydroxide resonance expected — 1105 cm"1 cannot be ambiguously identified due to overlying contributions within this spectral region (Shirtcliffe 2003). In any case, these observations are consistent with a hydrolysis step as an intermediate to forming the metal oxide.

Figure 3B shows the effect of temperature on IZO samples that were exposed to UV-Ozone treatment. Already at a temperature of 100 °C the oxidative treatment causes many of the aliphatic stabilizers that were integral to the solution deposition of the metal oxides to be removed. The broad and weak bands in the spectral region of 1300 - 1700 cm"1 do however indicate that residual N-H, C=0, CH2 and CH3 functionalities remain in the films. While the contributions of these signatures reduce with increasing annealing temperature, a gradual increase in the broad band between 3000-3600 1 and the peak at 1105 cm"1 is observed for temperatures up to 250 °C. The spectral region of both of the bands can be assigned to O-H and metal hydroxides, respectively (Shirtcliffe 2003). As there is no clear evidence of water or hydroxyl groups present in the samples following the UV-Ozone treatment, these observations suggests that hydrolysis of the metal is occurring at these higher temperatures due to atmospheric water vapours. Notably, ln-02 adducts have been reported at ~ 1084 cm"1 and similar species could in principle explain why there is a broad band peaked at ~ 1070 cm"1 following the UV-Ozone at 100 °C which possesses little hydroxyl or metal hydroxide content (Zehe 1979). At temperatures above 250 °C the contributions of both the hydroxyl and metal hydroxide content significantly decreased. This observation indicates that condensation is occurring at these temperatures to form metal oxides. A comparison between the UV-Ozone treated and the untreated samples show that the samples possess very similar chemical signatures following annealing at temperatures above 300 °C and 400 °C, respectively.

Overall, the FTIR of the acetylacetone based films with and without UV-Ozone confirms that both the acetylacetone, ethanolamine and the 2-methoxyethanol are coordinating the metal salts. The species are removed at increased annealing temperatures, with UV-Ozone acting to remove a substantial quantity of these stabilizers. In contrast to halide precursors, the decomposition of these precursors following UV-Ozone treatment is significantly cleaner.

X-ray photoelectron spectroscopy (XPS) was performed on IZO thin-films using acetylacetone precursors with and without UV-ozone treatment, then an additional thermal annealing step at different temperatures in air. A complete list of samples are provided in Table 2. XPS was utilized to map out the high resolution O 1s spectra to reveal the nature of the bonding within the first 10 nm of the surface.

Table 2. List of IZO thin-films prepared according to Example 2 using acac precursors and the thermal and oxidative conditions employed for their study through XPS.

Figure imgf000018_0001

Inspection of the high resolution 0 1s spectra gives direct evidence of the types of bonding associated with the oxygen existing within the films. Specifically, theoretical and experimental studies of ZnO have revealed that the O 1s contribution of Zn-OH and bulk Zn-O bonds are split by approximately 1.5-2;0 eV, with the Zn-OH being observed at a binding energy of -531.2-532 eV and the bulk ZnO being observed at 529.3 eV - 530.6 eV. To determine the nature of the bonding in the systems, Figures 4A and 4B show the high resolution O 1s spectra of the IZO films prepared using acetylacetone precursors without and with pre-thermal treatment UV-Ozone treatment, respectively.

The ACAC based IZO films show at similar trend to the CI based films with the exception that sample 11 does hint at the formation of cluster and instead a broad core- level binding peak centred at 531.7 eV is observed. This contribution is believed to be a contribution of bridging oxygen species originating from the ACAC and possibly the 2- methoxyethanol, as well as Zn-OH species. Increasing the annealing temperature causes a narrowing of the Zn-OH contribution, an indication of ACAC decomposition and 2-methoxyethanol evaporation, and a concordant increase in the bulk metal oxide peak. In comparison to samples 11-15, the rate bulk oxide formation is higher for this sample.

UV-Ozone treatment of the ACAC based IZO films shows a narrow Zn-OH contribution for sample 16. Annealing at 200 °C is found to result in an anomalous broadening of this peak, with little formation of bulk metal oxide. Higher temperatures, result in the analogous trend to the other samples, with a decrease in the hydroxlated contribution and an increase in the bulk metal oxide. Overall, the analysis of the O 1s core level binding energies shows that UV-Ozone treatment significantly enhanced the rate of bulk metal oxide formation compared to the hydroxylated contribution.

Example 3. Top contact bottom gate thin film transistors (TFT) were prepared via the deposition of metal oxide thin films prepared according to Examples 1-2 onto Gen. 5 TFT substrates that were purchased from the Fraunhofer IMPS. These substrates were n-doped silicon (doping at wafer surface n~3e-17 cm"3) 150 mm wafer semi-standard (675±40 μΐτι thickness). Gate dielectric layers were thermally oxidized 230 ±10 nm S1O2. Contacts were 30 nm of Au with 10 nm high work function adhesion layer (ITO) (structured by lift off techniques). Test chip sizes were 15 x 15 mm2. Channel width was fixed at 2000 μηη and channel lengths were varied as 2.5, 5, 10, 20 μητι, with a total of 16 devices in one test chip. Via Gate contact pads were 0.5 x 0.5 mm2 produced by a structured by lift off technique. Effect of Oxidative Treatment

To investigate the effects of the UV-Ozone treatment on the electronic properties thin film field effect transistprs (FETs) with thin films of IZO prepared according to both Example 1 and 2 were fabricated. FETs fabricated using IZO given by Examples 2 with UV ozone treated films possessed FET mobilities up 3 orders of magnitude higher compared to non-UV ozone treated films at an annealing temperature of 250°C (Figure 5a). The mobility was found to gradually increase for both UV-treated and untreated thin films with increasing annealing temperature. At an annealing temperature of 400°C, the mobility reached 11.11 and 4.5 cm2/Vs for UV ozone treated films and non-UV ozone treated films, respectively. Thin film FETs were also prepared using halide based precursors according to metal oxides prepared according to Example 1 , again with and without UV-ozone treatment. As shown in Figure 5b, there is an enhancement of mobility for the UV treated film annealed at low temperatures. Non UV-ozone treated devices demonstrate mobilities of 0.1 cm2A s for the films thermally annealed at 300°C for 60 minutes. With UV-Ozone treatment, it gradually rises to mobilities above 1 cm2/Vs. While the final effect of the oxidative treatment on FET performance is analogous to ACAC based precursors, the relative FET mobility of the IZO thin films prepared from halide based precursors is an order of magnitude lower.

Ideal transistors would possess high channel resistivity (low conductivity), high mobility, high on-off ratio and a low threshold voltage. Within IZO FETs prepared according to Example 1 and 2 and in conjunction with Example 3, higher mobilities at higher thermal annealing temperature, it was observed that channel conductivity goes up which leads to poor on-off ratio and large threshold voltage as depicted in Figure 6. Hence there is a trade-off of between conductivity and mobility. As an example, Figure 7 shows that for non-UV ozone treated thin films prepared according to Example 2 and thermally treated at 400°C demonstrate a mobility of 4.5 cm2A s, at the expense of very low channel resistivity. This results in large negative threshold voltage shifts and low on and off ratios. UV ozone treated films are found to posses significantly higher channel resistivity as well as high mobility at a low temperature of 300°C. Due to the lower processing temperature, the UV-ozone treated films thus permit good transistor characteristics to be realized.

To evaluate the effect of the UV-ozone temporal evolution on FET performance, the relative carrier mobility as a function of time of UV-ozone treatment time was determined using FETs fabricated with IZO thin films prepared according to Example 2. UV-ozone exposure is found to result in a 1 order of magnitude increase in the device mobilities within the 60 minute treatment range explored here (Figure 8). This arises because of the gradual oxidation of the thin-film through this oxidative treatment, reducing the carbon impurities and permitting metal oxide formation at lower temperatures. The evolution of carrier mobility of the thin film as function of thermal annealing time for a fixed UV-ozone treatment time of 60 mins (Figure 9) has also been studied. Effective annealing time was found to be between 30-60 minutes. The higher annealing times were found to result in lower threshold voltages, which is indicative of a reduced density of bulk and interface trap density. Outside of this annealing time range, the mobility was found to decrease.

The effective mobility observed in FET devices is highly dependent on the contact resistance values. Typically, these resistance values dominate over the channel resistance, thus reducing the effective FET mobility. If the intrinsic mobility in given channel material is high, one can design TFT with large channel length which will lead to very high channel resistance compared to the contact resistance. In this manner, the effective TFT mobility is maximized. To exploit this phenomenon, TFT devices using IZO films as prepared according to Example 2 with UV-Ozone treatment were fabricated and the W/L ratio was varied from 0.37 to 46.14. Figure 10 shows the transistor output characteristics with W/L ratio as the devices were Au source drain contact channel width of 45 μηι and channel length of 151 μιη giving W/L=0.3. From the respective slopes, 6 /D/6VG, device parameters: L, W, capacitance per unit area, C, of 10 nF/cm2, the field effect mobility^w) ~ 35 cm2/Vs was calculated. Output characteristics of thin film transistors characteristics is shown in Figure 11. Figure 12 shows the dependence of the FET mobility for these various W/L ratios. Consistent with the high intrinsic mobility of this IZO films, results show the highest mobility occurs at the experimental limit of W/L of 0.3, giving an FET mobility of 35 cm2/Vs. Clearly, smaller W/L ratios will result in even higher FET mobilities being realized.

Intrinsic charge carrier mobility from the measurement using four-point probes is shown in Figure 13 where, a mobility of 31.54 cm2/Vs was derived. From the very same devices with two probes measurement shows a mobility of 1 cm2 Vs. This contact resistance corrected channel conductivity measurement is consistent with the measurement of transistors with large L devices demonstrated in Figure 10, where effective contact resistance is reduced drastically.

As a final measure of the importance of oxidative treatment in metal oxide thin film FET, stress tests were performed of devices fabricated with IZO films prepared according to Example 2 that were UV-ozone treated and annealed at 300°C for 1 hour. The transfer curves at various stress intervals are shown in Figure 14. Figure 15 shows the corresponding mobilities and threshold voltages. As can be seen, the devices show reasonable stabilities under these stress conditions.

Given the high mobility of the channel materials demonstrated here, a unipolar voltage inverter circuit employing two transistors as shown in Figure 16 is demonstrated. One of the figures of merit, such as the transition frequency were also measured from a discrete transistor. Transition frequency was found to be - 2 kHz as shown in Figure 17. Given the mobility of the transistors were as high as 35 cm2A s, a transition frequency to at least in the order of MHz was expected. The reduced transition frequency is mainly due to large parasitic capacitance originated from the unpatterned semiconductor and gate dielectrics. This is demonstrated in the capacitance measurement of metal-insulator-metal devices where at higher frequency, capacitance drops drastically as shown in Figure 18.

Bottom contact transistors where Au electrodes are pre-patterned by using photo-lithography have also been investigated. The results are shown in Figure 19. The mobility is dropped by about factor of 10 with respect to top contact devices (Figure 10). This is due to the associated large channel resistance of the device. Finally the device geometry where standard S1O2 gate dielectric is replaced by ultrathin Alumina gate dielectric with transistors operating at voltage as low as 1V was investigated as shown in Figure 20.

Overall, in the process described the applicant has introduced an oxidizing step on as deposited amorphous metal oxide thin-films prior to thermal treatment which has been found to significantly improve the electronic properties of the resulting amorphous metal oxide thin films. When followed by a heat treatment step at a nominal temperature below 400°C, thin-film amorphous metal oxide films are fabricated, which when used within field effect transistor devices possess have high charge mobilities compared to solution-based amorphous metal oxide materials that do not undergo this oxidizing pre- treatment step. Using this approach, thin film transistors with a field effect mobility of 35 cm2/vs have been demonstrated. It will be appreciated that the thin films produced by the method of the invention find application in a range of electronic devices including but not limited to photovoltaic cells (as the charge blocking and charge transport layers), light emitting diodes (as the light emitting and charge transport layers), transistors (as the semiconducting layer between the source and drain electrodes on the surface of gate insulator), inverters/ring oscillators, photodetectors (as the light absorbing and charge transport layers), lasers (as the light emitting and charge transport layers), light-emitting transistor (as the light emitting and charge transport layers), thermistor (as the temperature responsive and conductive layers), memristor (as the magnetic responsive layer), electrical junctions/contacts (as the conductive material), sensors, flat panel displays, and flexible displays.

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

References

Menon2011 - Menon, R.; Gupta, V.; Tan, H. H.; Sreenivas, K.; Jagadish, C.; J. Appl Phys. 109, 064905, (2011 ).

Coates2000 - Coates, J. Interpretation of Infrared Spectra, A Practical Approach, Encyclopedia of Analytical Chemistry, John Wiley & Sons, Ltd, (2000).

Silva1999- Silva, C. F. P.; Duarte, M. L. T. S.; Fausto, R.; J. Mol. Struct. 482-483, 591-599, (1993).

Pinchas1967 - Pinchas, S.; Silver, B. L.; Laulicht, I.; J. Chem. Phys. 46 (4), 1506-1510, (1967).

Shirtcliffe2003 - Shirtcliffe, N. J.; Stratmann, .; Grundmeier, G.; Surf. Interface Anal. 5, 799-804, (2003).

Zehe1979 - Zehe, M. J.; Lynch, D. A. Jr.; Kelsall, B. J.; Carlson, K. D.; J. Phys. Chem., 83, 656-664, (1979). Tseng2010 - Tseng, C.-L; Chen, Y.-K.; Wang, S.-H.; Peng, Z.-W.; Lin, J.-L.; J. Phys. Chem. C 114, 11835- 11843, (2010).

Yoshida1993 - Yoshida, H.; Takikawa, K.; Ohno, K.; Matsuura, H.; Journal of Molecular Structure, 299, 141- 147, (1993).

Ismail1991 - Ismail, H. M.; 21 , 315-326, (1991). Hosono2010 - H. Hosono, in Handbook of Transparent Conductors, Chap. 13, D. Ginley, H. Hosono, and D. Paine, Editors, Springer, New York (2010).

Seo2009 - S-J. Seo, C. G. Choi, Y. H. Hwang, B-S. Bae, J. Phys. D: Appl. Phys. 035106, 42 (2009).

Banger2011 - K. K. Banger, Y. Yamashita, K. Mori, R. L. Peterson, T. Leedham, J. Rickard and H. Sininghaus, Nature Materials 45, 10 (2011). Minami1995 - T. Minami, H. Sonohara, T. Kakumu and S. Takata, Jpn. J. Appl. Phys. L971-974, 34 (1995).

Kim20 1 - M-G. Kim, M. G. Kanatzidis, A. Facchetti and T. J. Marks, Nature Materials 382, 10 (2011).

Kamiya2010 - T. Kamiya, K. Nomura and H. Hosono, Sci. Technol. Adv. Mater. 044305, 11 (2010).

Hang2011 - S-Y. Han, G. S. Herman, and C-H. Chang, J. Amer. Chem. Soc. 5166, 133 (2011).

Claims

1. A method of preparing an amorphous metal oxide thin film, the method including: providing a fluid medium including an inorganic material dispersed in a solvent; providing a substrate; contacting the fluid medium with the substrate to produce a thin film on the substrate; and
. annealing the thin film; wherein the inorganic material is a non-halide containing metal salt; and wherein the method further includes subjecting the thin film to an oxidative treatment to release volatile organic components from the thin film, prior to the annealing step.
2. The method according to claim 1 , wherein the step of subjecting the thin film to an oxidative treatment includes exposing the thin film to an environment including one of H2O, 02, O2 plasma, O3, plasma O3, ultraviolet 03, N20 and plasma N20.
3. The method of claim 1 or 2 wherein the oxidative treatment is provided by ultraviolet O3 (UV ozone).
4. The method of claim 3 wherein the intensity of the UV ozone with wavelength 185nm is 300W/cm2.
5. The method of any preceding claim, wherein the inorganic material is selected from metal carboxylates, alkoxides, diones, cubanes, amides, nitrates, sulfates, hydroxides, tri-thiocarbamates, xanthates, carbamates, and carbonyls.
6. The method of claim 5, wherein the metal salt is one of Gallium, Indium, Zinc or Tin metal centre with an alkoxide, carboxylate or dione stabilizer.
7. The method of any preceding claim, wherein the solvent is one of water, alcohols, aminoalcohols, carboxylic acids, ethers, hydroxyesters, aminoesters, amides, sulfoxides and mixtures thereof.
8. The method of any preceding claim further including adding an additive component to the fluid medium to induce changes in metal coordination, redox states, solubility, thermal stability, and chemical reactivity.
9. The method of claim 8, wherein the additive is selected from the group including alanine, ammonia, aniline, imidazole, pyridine, pyrimidine, pyrazine, piperidine, piperazine, quinoline, 1 ,3 thiazole, nitrates, imides, amides, primary amines, secondary amines and tertiary amines of an linear alkyl, branched alkyl, aromatic, carboxylate, alcoholic, carboxylic, ester, ether, diamines and or mixtures thereof, water, linear and branches alkyl carboxylates, linear and branches alcohols, esters, ethers, and beta- diketones.
10. The method of any preceding claim, wherein the fluid medium is deposited on the substrate component by spin-coating, ink-jet printing, spray coating, gravure printing, or slot-die coating.
11. The method of any preceding claim wherein the thin film has a thickness less than 100nm.
12. The method of any preceding claim wherein the thin film has a thickness less than 50nm.
13. The method of any preceding claim wherein the thin film has a thickness in the range 10-30nm.
14. The method of any preceding claim wherein the step of oxidising the thin film is performed at a substrate temperature between room-temperature and 150°C.
15. The method of any preceding claim wherein the step of annealing the thin film is conducted at a temperature between 200 and 400°C.
16. The method of any preceding claim wherein the step of annealing is performed in an ambient air, dry air, oxygen, nitrogen, argon, or vacuum environment.
17. The method of any preceding claim wherein the step of annealing is performed by a radiative heat source, a laser, a pulsed flash of light or other suitable means.
18. The method of any preceding claim wherein the step of annealing is performed for less than 1 hour.
19." The method of any preceding claim wherein the substrate is a mechanically stable, flexible, transparent or semi-transparent substrate.
20. The method of claim 19 wherein the substrate is a flexible polymer.
21. The method of claim 19 wherein the substrate is a metal foil.
22. A thin film transistor produced by the method of any one of claims 1 -21.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016027608A (en) * 2014-03-14 2016-02-18 株式会社半導体エネルギー研究所 Semiconductor device
CN105959000A (en) * 2016-04-22 2016-09-21 电子科技大学 Memristor-based rapid start-up crystal oscillator

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080099809A1 (en) * 2006-10-26 2008-05-01 Elpida Memory, Inc. Semiconductor device having a capacitance element and method of manufacturing the same
US20090206341A1 (en) * 2008-01-31 2009-08-20 Marks Tobin J Solution-processed high mobility inorganic thin-film transistors
WO2009119968A1 (en) * 2008-03-27 2009-10-01 Industry-Academic Cooperation Foundation, Yonsei University Oxide semiconductor thin film and fabrication method thereof
WO2011078398A1 (en) * 2009-12-25 2011-06-30 Ricoh Company, Ltd. Field-effect transistor, semiconductor memory, display element, image display device, and system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080099809A1 (en) * 2006-10-26 2008-05-01 Elpida Memory, Inc. Semiconductor device having a capacitance element and method of manufacturing the same
US20090206341A1 (en) * 2008-01-31 2009-08-20 Marks Tobin J Solution-processed high mobility inorganic thin-film transistors
WO2009119968A1 (en) * 2008-03-27 2009-10-01 Industry-Academic Cooperation Foundation, Yonsei University Oxide semiconductor thin film and fabrication method thereof
WO2011078398A1 (en) * 2009-12-25 2011-06-30 Ricoh Company, Ltd. Field-effect transistor, semiconductor memory, display element, image display device, and system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016027608A (en) * 2014-03-14 2016-02-18 株式会社半導体エネルギー研究所 Semiconductor device
CN105959000A (en) * 2016-04-22 2016-09-21 电子科技大学 Memristor-based rapid start-up crystal oscillator

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