Thermal Annealing Of Films Research Articles

Distribution of Process Induced Traps in Ozone Annealed Indium-Gallium-Zinc-Oxide Film Determined From Noise Characterization

Space-energy distribution of process induced traps was extracted from random telegraph noise (RTN) characterization on ozone (O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) annealed Indium-Gallium-Zinc-Oxide (IGZO) metal-oxide-metal (MOM) capacitors. It was found that, O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> anneal increases both deeper and shallower traps in IGZO all the way to conduction band edge (CB) compared to the as-deposited film, and results in higher aggregate trap density as found from low frequency noise measurement. Extracted trap distribution was benchmarked with that in as-deposited and thermal annealed films, and was found convenient to interpret low field current degradation in IGZO due to O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> anneal.

Hole-injection barrier across the intermolecular interaction mediated interfacial DNTT layer

The electronic structures and morphology of dinaphthothienothiophene (DNTT) thin films on highly oriented pyrolytic graphite (HOPG) and polycrystalline Au (pc-Au) substrates have been investigated using photoelectron spectroscopy and atomic force microscopy techniques to better correlate the charge-injection barrier with the interfacial structure. DNTT molecules follow Stranski–Krastanov-type growth mode, i.e., highly-dewetted islands/fibers above a relatively-wetted interfacial layer, on both the substrates, but distinctively different electronic structures. On the HOPG surface, the as-grown and thermal-annealed films show a broad and a sharp highest occupied molecular orbital (HOMO) bands, respectively. On the pc-Au surface, a significantly split HOMO band and a reduced hole-injection barrier are observed in a monolayer thick film, for the first time, which are absent in other thick films. Such splitting indicates a presence of a strong intermolecular interaction in the interfacial layer, presumably due to the frontier π-orbital overlapping arising from partially-covered densely-packed herringbone-like arranged molecules. The dewetted-fibers seem to form with up-right oriented molecules having negligible interaction, which desorb easily by thermal annealing to retain the highly-stable interfacial layer. The reduction of the hole-injection barrier at the DNTT/pc-Au interface, due to the formation of such interfacial layer having strong intermolecular interaction, has an immense importance in increasing the charge-injection efficiency from a practical electrode.

Boosted Charge‐Carrier Transport in Triple‐Cation Perovskites by Ultrasonic Vibration Post Treatment

AbstractUltrasonic vibration imposed on the substrate of a drying perovskite solution film has previously been proposed as a nearly annealing‐free method to improve film quality and thus the photovoltaic performance for perovskite solar cells. However, an in‐depth understanding of the underlying mechanism of the improved film quality via ultrasonic vibration is still lacking. In this work, the effects of substrate vibration post treatment on the carrier lifetime and mobility are studied in triple‐cation perovskite films. With 80 s of annealing‐free vibration, the perovskite film demonstrates much stronger photoluminescence intensity and much longer carrier lifetime up to 2.634 µs, 2 orders of magnitude longer than that of the thermal annealed films. Optical pump terahertz probe spectroscopy reveals that the charge‐carrier mobility increases to 121 ± 44 cm2 V−1 s−1 when subjected to 80 s vibration followed by annealing. Such mobility is about 80 ± 40 cm2 V−1 s−1 higher than that of other polycrystalline organic–inorganic hybrid perovskite thin films of similar composition. The diffusion length is improved to nearly 1.5 times. The new understanding on the vibration‐induced charge‐carrier transport properties paves the way for the application of ultrasonic vibration toward the performance improvement of perovskite‐based electronic devices.

Organic Light-Dependent Resistors with Near Infrared Light-Absorbing Conjugated Polymer Films

Here we demonstrate near-infrared (NIR) light-sensing organic light-dependent resistors (OLDRs), so-called organic photoresistors (OPRTs), which consist of solution-processed NIR light-absorbing films of poly[{2,5-bis(2-octyldodecyl)-3,6-bis(thien-2-yl)-pyrrolo[3,4-c]pyrrole-1,4-diyl}-co-{2,2′-(2,1,3-benzothiadiazole)-5,5′-diyl}] (PODTPPD-BT). The present NIR-OPTRs were fabricated in a planar geometry by forming two aluminum electrodes in parallel on the PODTPPD-BT films with three different thicknesses (40, 100, and 160 nm). The sensing characteristics of NIR-OLDRs were examined using a NIR laser diode featuring a wavelength (λ) of λ = 905 nm that is one of the popular wavelengths employed for light detection and ranging (LiDAR) systems. In the dark condition, the electrical resistance (RH) of devices in the horizonal direction was marginally changed with the thickness of PODTPPD-BT films. However, the RH values were remarkably reduced upon the NIR light illumination for all devices and were strongly dependent on the NIR light intensity. Thermal annealing of devices delivered greatly improved current responses leading to a huge RH reduction (by ca. 80%) and excellent sensing stability, even though only 49% improvement in RH was achieved by thermal annealing of films.

Selective Morphological and Polymorphic Control of CL-20 Thin Films Using Meniscus-Guided Coating

Controlling the morphology and crystal structure of energetic materials (EMs) is crucial for predictable performance and stability under operational and accidental scenarios. In this work, an EM of interest, hexanitrohexaazaisowurtzitane (CL-20), was crystallized as thin films using a meniscus-guided coating technique termed solution shearing. We observed four distinct morphological regimes within the parameter space, as well as regions with selective formation of the β and γ polymorphs of CL-20. The thin films ranged in thickness from 79 nm to 2.2 μm and in surface coverage from 36.2 to 99.9%. Thermal annealing of films at 180 °C promotes a β-to-γ phase transformation for films with thicknesses >500 nm. Water vapor annealing of films results in a phase transition to α-hydrate. We were unable to attain the ε polymorph in our thin films across all processing conditions, including dissolution and recrystallization, which preferentially forms the β polymorph. Therefore, we show that thin-film confinement stabilizes the β polymorph of CL-20 over the ε polymorph. The results of this work have important implications for EM composites as interfacial recrystallization of the stable bulk ε polymorph may result in the formation of the β polymorph as a thin film at the interface, changing the EM stability. We show that the solution shearing technique provides a promising platform for the study of the interfaces between energetic crystals and polymers in composites.

End-Capping π-Conjugated Naphthodithiophene Diimide (NDTI)-Based Triads with Noncovalent Intramolecular S···O Interactions: A Route towards High-Performance Solution-Processable Air-Stable n-Type Semiconductors

Introducing noncovalent intramolecular interactions into functional π-conjugated organic molecules or polymers is a useful method to improve the performance of organic semiconducting devices. In this study, two small molecules based on naphthodithiophene diimide (NDTI), NDTI-BTIC1 and NDTI-BTIC2, were successfully designed and synthesized by covalently connecting an electron-deficient NDTI-core and two 3-(dicyanomethylidene)-indan-1-one (IC) groups with thiophene substituted by an alkoxy chain or alkyl chain, respectively. Density functional theory (DFT) calculations on the optimized geometries of the triads predict that the existence of noncovalent intramolecular S (thiophene)···O (alkoxy) interactions is possible in NDTI-BTIC1. The molecular orbital distributions of NDTI-BTIC1 and NDTI-BTIC2 show that the lowest unoccupied molecular orbitals (LUMOs) are delocalized in the whole molecule, implying the possibility to show n-type transport characteristics. The two molecules further demonstrated LUMOs at a low altitude of −4.37 to −4.45 eV, low enough for the stable transmission of electrons in the atmosphere. The solution-processing method was used to prepare transistors based on the two molecules’ bottom-gate top-contact (BGTC), which exhibited unipolar n-type field-effect transistor (FET) characteristics in the air. The FET performance of NDTI-BTIC1 is higher than that of NDTI-BTIC2 in both the as-spun and thermal annealed films, possibly attributed to the existence of noncovalent intramolecular S···O interactions in NDTI-BTIC1. Moreover, the maximum electron mobility of NDTI-BTIC1 obtained at 150 °C thermal annealing is improved by one order of magnitude compared to that of NDTI-BTIC2, being 0.17 and 0.085 cm2 V–1 s–1, respectively. The transport difference of the two molecules was proved by film morphology analysis. The results show that constructing noncovalent intramolecular S···O conformational locks between the TIC unit and NDTI can improve the organic field-effect transistor (OFET) devices’ performance through reasonable molecular design strategies.

(Invited) Conformal Deposition of Li-Based Thin Films for 3D Lithium-Ion Microbatteries

Lithium-ion batteries have been the premiere power source in the mobile electronics industry due to their superior energy density and cycle life as compared to other battery chemistries. In the Era of the Internet of Things (IoT) there is an increasing need to find a viable power source to support millimeter-size and smaller scale devices in the fields of environmental sensing, biomedical devices, and wearable electronics. Three-dimensional battery architectures mitigate the limitations of traditional thin film batteries through improvement of ion transport properties allowing for higher areal loading of active materials. Atomic layer deposition not only offers the ability to synthesize a wide range of functional materials, but crucially is a non-line-of-sight deposition technique that allows for conformal deposition necessary for fabrication of 3D lithium-ion batteries. In this work, two ALD processes were developed to synthesize conformal thin films applicable to 3D battery fabrication—LiAlSiO4, a solid-state electrolyte, and LiMn2O4, a high-rate thin film cathode.LiAlSiO4 is a solid-electrolyte of interest, in which its quartz-like framework produces unique 1D channels for Li-ion transport along the c-axis, exhibiting ionic conductivities as high as 4.7x10-5 S/cm at room temperature,1, 2 where the ionic conductivity in its thin film form has shown to increase upon decreasing thicknesses, 3 In this work, ALD of LixAlySizO was demonstrated with careful tuning of the stoichiometry to allow for crystallization into the ionically conductive β-Eucryptite LiAlSiO4 phase. The rapid thermal annealed ALD film developed a well-defined epitaxial relationship to the silicon substrate: β-LiAlSiO4 (12 ̅10) || Si (100) and β-LiAlSiO4 (101 ̅0) || Si(001). The extrapolated room temperature ionic conductivity was found to be 1.2 x 10-7 S/cm in the [12 ̅10] direction with an activation energy of 0.63 eV, as compared to amorphous ALD LASO films with ionic conductivities on the order of 10-9 S/cm.Beyond the electrolyte layer, an equally crucial material is a thin film cathode with optimal interfacial properties to ensure homogeneous active material utilization, adequate cycle-life, and high rate performance. To realize this goal, LiMn2O4 was demonstrated utilizing O2 plasma and Tris(2,2,6,6Tetramethyl-3,5-heptanedione) Mn(III), where lithium incorporation was performed through a thermal ALD LiOtBu/H2O process. Thin films with stoichiometries of Li1+xMn2-xO4, where x>0 were observed (as-characterized via XPS) with LiOH ALD sub-cycle percentages lower than 1% of the total ALD supercycle. LiMn2O4 thin films exhibited great rate capability (66% capacity retention after increasing the rate from C/2 to 50C) as well as capacity retention (97% capacity retention after 100 cycles at 5C).Lastly, a proof-of-concept nanobattery consisting of a SiGe nanowire (anode) coated with LixAlySizO (electrolyte) and LiMn2O4 (cathode) was fabricated. Both materials show great promise for direct integration with three-dimensional lithium-ion microbatteries.1. V. Thangadurai and W. Weppner, Ionics 8 (3), 281-292 (2002). 2. P. G. Bruce, Solid State Electrochemistry. (Cambridge University, Press, 1995).3. S.-i. Furusawa, H. Tabuchi and T. Tsurui, Solid State Ionics 178 (15), 1033-1038 (2007).

Directed Self-Organization Ensured Enhancement of Charge Carrier Mobilities in a Star-Shaped Organic Semiconductor.

Controlled self-organization of organic semiconductor molecules into specifically desired architectures on substrates of interest is one of the most imperative challenges faced in the fabrication of high-performance organic electronic devices. Herein, we report the self-organization of a star-shaped molecule FDT-8 into a highly favored structure, namely, a vertical stack. Thermal annealing of films of FDT-8 deposited on PEDOT: PSS coated ITO substrates was observed to assist the organization of the molecules into columnar stacks. A significant enhancement in the hole (≈50-fold) and the electron (≈13-fold) carrier mobility was observed in single-carrier devices upon thermal annealing that could be attributed to the aforementioned self-organization. The ability of these molecules to spontaneously self-organize was utilized to fabricate bilayer light-emitting devices.

Solvent vapor annealing for poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) thin films toward transistor fabrication

Solvent vapor annealing (SVA) was examined for poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT-C14) thin films as the activate layer of top-contact, bottom-gate transistors. SVA with chlorobenzene vapor was performed on different types of PBTTT-C14 films; pristine films on SiO2, thermally-annealed films on SiO2, and thermally-annealed films on alkylsilane-modified SiO2. Solvent vapors penetrated into the PBTTT-C14 films and caused some similar effects as conventional post-thermal annealing, such as reduced molecular lamellae spacing and increased field-effect mobility. Additionally, the hole mobility of the thermally-annealed film on alkylsilane-modified SiO2 was increased by SVA with relatively shorter duration, even without any obvious shifts in lattice spacing and optical absorption bands of the films. This means that SVA only for the film surface and the upper part of the organic active layer may be effective for improving electrode contact interfaces in top-contact transistors. The roles of SVA for tailoring structures and field-effect carrier transport in PBTTT-C14 films are considered.

Strong Disorder in HgCdTe Studied with Optical Methods and X-Ray Diffraction

Optical transmission, photoluminescence, and X-ray diffraction have been used for studying structural disorder in Hg1-xCdxTe (x=0.3–0.4) films grown by Molecular-Beam Epitaxy on GaAs and Si substrates. According to all three methods, studied films immediately after the growth showed quite different scale of the disorder. After thermal annealing films showed similar optical properties, yet their structural properties remained different. It appears that the ability of Hg1-xCdxTe to gain good optical quality under annealing for considerably disordered initial material is not directly structure-related.

How to Make Dense and Flat Perovskite Layers for &amp;gt;20% Efficient Solar Cells: Oriented, Crystalline Perovskite Intermediates and Their Thermal Conversion

Abstract CH3NH3PbI3 (MAPbI3) perovskite layers can be obtained by thermal annealing thin films of the intermediate dimethyl sulfoxide (DMSO) intercalated complex, MA2Pb3I8·2DMSO. In the present work, the formation, structure, and thermal transformation of the intermediate complex in both bulk and thin film form is examined in detail. The grain size and orientation of the intermediate crystallites in the solvent-intercalated thin film material is shown to directly influence the flatness of the annealed perovskite layer. Flat-lying orientation of the small needle-like intermediate crystallites is found to yield dense and flat perovskite layers. Optimized spin coating and annealing processes are developed for the formation and thermal conversion, respectively, of the intermediate film. Based on these methods, MAPbI3 perovskite solar cells with high power conversion efficiency (maximum ∼20.3%) were obtained with high reproducibility.

Effect of rapid thermal annealing on the structure, microstructure and magnetic properties of Fe thin films

This paper reports the structure, microstructure and magnetic properties of as-deposited and rapid thermal annealed Fe thin films. Rapid thermal annealing was carried out at 550 °C for different time intervals such as 2, 5, 10, 20 and 30 min. The as-deposited and rapid thermal annealed films were found to exhibit A2 type bcc structure. However, microstructural studies indicated formation of Fe–Si phase for the annealed Fe films. Surface roughness estimated from atomic force microscopy studies displayed an increase in surface roughness with increase in annealing time. Room temperature magnetization studies showed a predominant in-plane magnetic anisotropy for all the films. In addition to this presence of strong out-of-plane anisotropy coupled with in-plane magnetization was clearly evidenced from the considerable increase in the out-of-plane coercivity with increase in annealing time. Magnetic force microscopy studies further confirmed the presence of out-of-plane magnetic anisotropy. Magnetic domain imaging studies showed long period band domain patterns with 180° domain wall for the as-deposited film. The band domains were found to get branched with increase in annealing time. From the hysteresis loops and domain imaging studies it was clear that the magnetization reversal is dominated by domain wall motion.

Effect of varying the vanadium thickness layer of V2O5/V/V2O5 film on its microstructural and thermochromic properties

In this study, V2O5/V/V2O5 sandwich-structured films were deposited on glass substrates by electron beam evaporation. The thickness of the first (bottom) V2O5 layer was 40 nm and the last (top) layer was 20 nm, while that of the sandwiched vanadium layer varied up to 12 nm for different samples. The effects of varying the thickness of the sandwiched vanadium layer on microstructural and thermochromic properties of the as-deposited and thermal annealed films were investigated. Ultrahigh-resolution scanning electron microscopy revealed the presence of nanostructures with various irregular shapes on the surfaces of all films. Also, the atomic force microscopy revealed an average roughness of ∼10–38 nm for increasing thickness of the sandwiched vanadium layer. X-ray powder diffraction measurements showed the presence of the monoclinic VO2 (M) crystal structure of the films with (011) preferred orientation at 27.94° for both 7 and 12 nm thicknesses of the sandwiched vanadium layers. The varying thickness of the sandwiched vanadium layers enhanced phase transition temperature values to ∼33.92 and ∼29.11 °C for both 7 and 12 nm thicknesses of the sandwiched layers, respectively. These enhanced transition temperature values, as a result of thickness variation of the sandwiched vanadium layers, pointed toward utilization of this method in the successful synthesis of VO2 films for thermochromic windows application and optoelectronics.

Solid-Phase Interaction in Fullerite-Bismuth Films in the Process of Thermal Annealing

The changes in the structure, surface roughness, and phase composition of thin fullerite-bismuth films deposited onto substrates from oxidized single-crystal silicon under thermal action in vacuum are studied by means of atomic-force microscopy and X-ray diffraction analysis. It is established that as-deposited bismuth films have a polycrystalline structure in the form of thin plates with an average arithmetic surface roughness of 13.72 nm. The thermal annealing of films at 490 K results in fractional recrystallization of the films and a decrease in the average arithmetic roughness to 12.74 nm. After thermal action at 540 K, the average arithmetic roughness of the films is 10.32 nm, the crystallites take the form of globules with an average size of 100 nm, new X-ray reflections appear on the X-ray patterns that indicate the formation of bismuth fulleride.

Superconductivity in nanocrystalline tungsten thin films growth by sputtering in a nitrogen-argon mixture

We report on the structural and superconducting properties of nanocrystalline tungsten thin films growth by sputtering at room temperature with an N2:Ar mixture (N2 from 3% to 50%). The crystalline phases were identified by comparing as-grown and thermal annealed thin films. For N2/(Ar + N2) mixtures between 3 and 10%, the films display nanocrystalline β-W phase. Coexistence of β-W and W2N phases are observed for gas mixtures with N2 between 20% and 40%. A detailed study of the superconducting properties as function of the thickness was performed for W films growth with 8% N2 mixtures. For this concentration, the nitrogen atoms increase the disorder at the nanoscale reducing the grain size and avoiding the crystallization of α-W. The superconducting critical temperature (Tc = 4.7 K) is thickness independent for films thicker than ~17 nm. Below this thickness, the Tc value decreases systematically being 3.1 K for 4 nm thick films. Our study provides a simple method for the fabrication of nanocrystalline β-W thin films with potential applications in superconducting devices.

Comparative surfacing studies of sputtered and thermal annealed ZnO films wet etched with NH4Cl and acidic etchants

The wet etchings of as-grown and thermal annealed ZnO films were carried out by using NH4Cl and acidic etchants respectively. The lateral profiles and side faces of the etched ZnO samples were exhibited by profiler and SEM measurements. NH4Cl etchant can avoid W-like lateral profile and eave-like slope at the side face of the etched ZnO patterns for both as-grown and post-annealed ZnO samples. The etching rate has been compared between NH4Cl etchant and acidic etchants for both as-grown and post-annealed ZnO samples. NH4Cl etchant can maintain slower etching rate with higher NH4Cl concentration. The thermal annealing procedure can be helpful to achieving uniform etching surface, and the etching rates of the annealed ZnO samples are even slower, which can be explained by the better crystallinity and lower density of oxygen vacancy.

Chemical modification with orthophosphoric acid enhances surface-charge stability on polypropylene electrets

The low surface-charge stability of polypropylene (PP) frequently limits its application as an electret material. In this paper, we demonstrate how the treatment of PP-film surfaces with orthophosphoric acid (H3PO4) enhances their charge stability. To discriminate between the effects of chemical modification and thermal treatment, as-received and annealed PP films are used as reference samples. The electret properties of treated and non-treated PP films are characterized with thermally stimulated discharge (TSD) and isothermal surface-potential decay (ISPD) experiments, from which considerable improvement in thermal and temporal charge stability is observed for samples modified with H3PO4. The half-value temperature (T1∕2) observed on TSD curves of chemically treated PP increases to 131 and 145 °C for positive and negative charges, respectively. The enhancement might be attributed to the phosphoric compounds detected on the H3PO4-modified surfaces via attenuated-total-reflection infrared spectroscopy. Deeper surface traps formed at the “foreign” phosphorus-containing structures are able to capture the charges over longer time periods and at higher temperatures, thus leading to significant improvements in the temporal and thermal surface-charge stabilities of PP electrets.

Magnetic behaviour of as-deposited and rapid thermal annealed Pr-Fe thin films

In the present work structure, microstructure and magnetic behaviour of e-beam evaporated Pr-Fe thin films was investigated in as-deposited and rapid thermal annealed conditions. The films were deposited on Si 〈100〉 substrates at room temperature. Structural studies carried out employing X-ray diffraction indicated that the as-deposited films were completely amorphous in nature. Upon rapid thermal annealing, presence of Fe phase could be observed from the X-ray diffraction patterns. Field emission gun scanning electron microscopy studies confirmed the presence of Fe nano-crystalline grains surrounded by amorphous Pr-Fe matrix with the number of nucleation sites increasing with increasing annealing temperature. Magnetization studies showed weak ferromagnetic behaviour for the as-deposited films whereas rapid thermal annealed films exhibited strong in-plane magnetic anisotropy owing to the presence of Fe nano-crystalline grains. Saturation magnetization estimated from the in-plane magnetization curves was found to increase with increasing annealing temperature up to 450°C although with further increase in annealing temperature to 550°C it decreased. A minimum coercivity of about 1.6kA/m was observed for the Pr-Fe film annealed at 450°C. Magnetostriction measurements indicated increase in magnetostriction with increasing annealing temperature up to 450°C. A maximum magnetostriction of about 100μ-strains was achieved for the film annealed at 450°C.

Structural and optoelectronic properties of CdCl2 activated CdTe thin films modified by multiple thermal annealing

Traditional CdCl2 thermal treatment of CdTe/CdS heterostructure results in grain growth, sintering and incorporation of Cl into CdTe lattice, substantially improving performance of the cells. The process is complicated by high vapor pressure of CdCl2 and presence of oxygen. Considering volatility of CdCl2 and presence of residual oxidation products we provide systematic investigation results on the influence of subsequent multiple annealing in hydrogen (H2), vacuum and closed isothermal conditions on the properties of CdCl2 activated CdTe films (thickness 2μm) deposited by close spaced sublimation at low (250°C) and high (500°C) substrate temperature onto roughened glass. Structural and optoelectronic properties of thermal annealed films were compared. High resolution X-ray analysis demonstrates the shift of the main (111) peak in accordance with mobility of CdCl2 impurity between ambient and CdTe crystal in good correlation with optoelectronic properties. CdCl2 activated CdTe films have high resistivity and high dark to light resistance ratio. Subsequent hydrogen and vacuum thermal annealing increases the resistivity and photoconductivity of the films. The dark resistivity has been sharply decreased by about four orders of magnitude in result of isothermal annealing at 600°C. By controlling the thermal annealing conditions, substantial improvement of CdTe optoelectronic properties has been achieved.

High performance solution-deposited bilayer channel indium–zinc-oxide thin film transistors by low-temperature microwave annealing

We report the high-performance solution-deposited indium–zinc-oxide (IZO) TFTs with a bilayer channel structure fabricated at low temperature using a microwave irradiation (MWI) post-deposition annealing (PDA) process. Although, the MWI process temperature (89 °C) was much lower than the baking temperature (180 °C) of solution precursors, the microwave irradiated film has comparable chemical binding states to the thermal annealed film at 600 °C. For the enhancement of channel performance, channel engineering was applied by exploiting bilayer channel with different composition-ratios of In and Zn (In:Zn = 3:1, 2:1, 1:1, 1:2 and 1:3). Bilayer channel IZO TFTs consist of electron transfer channel layer and capping layer. The electrical characteristics for various combinations of bilayer channel were investigated. As a result, the transfer channel layer of In:Zn = 1:1 and the capping layer of In:Zn = 3:1 turned out to be effective for improving the mobility, subthreshold swing and hysteresis of IZO TFTs. We found that the electrical characteristics of solution-deposited IZO TFTs can be greatly improved by using bilayer channel structure and low temperature MWI-PDA process.