IZO Thin Films Research Articles

Some physical investigations on In-doped ZnO films prepared by RF magnetron sputtering using powder compacted target

Indium-doped zinc oxide thin films (IZO) at different percentages (2–5 wt%) were deposited on p-Si(100) and glass substrates at room temperature using powder compacted target. The effect of In concentration on the structural, optical and electrical properties of the IZO thin films were investigated. XRD analysis revealed that all films consist of single phase ZnO and were well crystallised in wurtzite phase with the crystallites preferentially oriented towards (002) direction parallel to c-axis. Doping by Indium resulted a noticeably change in the optical band gap energy. Hall effect measurements show that all films present an n-type conduction. The lowest obtained resistivity of the IZO films is 5.35 × 10− 3 Ω cm. From the I–V and C–V characteristics, we investigated the ideality factor, the donor concentrations, the barrier height and the series resistance of the ZnO/p-Si heterojunction. Finally, all results have been discussed in terms of the Indium doping concentration.

溶胶凝胶法制备透明IZO薄膜晶体管

The amorphous InZnO(a-IZO) thin films were prepared by sol-gel technology,and thin film transistors(TFTs) were further fabricated by employing the IZO films as the active channel layer after low temperature(300 ℃) annealing treatment.The influence of indium concentration on the electrical properties of IZO thin films and the IZO-TFTs was investigated in this paper.The results revealed that the IZO film was amorphous,surface was uniform and smooth,grain about 20 nm,and the visible average optical transmittance was more than 85%.IZO-TFT with a threshold voltage of 1.3 V,a mobility of 0.24 cm2·V-1·s-1,and a Ion∶Ioff current ratio of 105 was obtained when n(In)∶n(Zn)=3∶2.

High-Performance Oxide Thin-Film Transistors Using a Volatile Nitrate Precursor for Low-Temperature Solution Process

Solution-processed InZnO (IZO) thin-film transistors (TFTs) are fabricated using a volatile metal nitrate precursor (Np) with annealing at 300°C. Because the metal Np decomposes at low temperatures, metal oxide bonds were formed, and the organic residue in the oxide thin films was evaporated at low temperature. At 300°C , the IZO thin films with Zn Np were of higher quality than those with Zn acetate precursor due to the reduced atomic disorder and evaporation of residual organics. The mobility of the IZO TFTs with Zn Np was 1.92 cm2/V·s at 300°C annealing.

Electronic and optical properties of hafnium indium zinc oxide thin film by XPS and REELS

The electronic and optical properties of GaInZnO (GIZO), HfInZnO (HIZO) and InZnO (IZO) thin films on glass substrates were investigated using X-ray photoelectron spectroscopy (XPS) and reflection electron energy loss spectroscopy (REELS). XPS results show that HIZO, GIZO, and IZO thin films have mixed metal and oxide phases. REELS spectra reveal that the band gaps of GIZO, HIZO, and IZO thin films are 3.1eV, 3.5eV, and 3.0eV, respectively. These band gaps are consistent with optical band gaps determined by UV-Spectrometer. The optical properties represented by the dielectric function ɛ, the refractive index n, the extinction coefficient k, and the transmission coefficient T of the GIZO, HIZO and IZO thin films were determined from a quantitative analysis of REELS spectra. The transmission coefficient was increased by 4% for the HIZO compound incorporating Hf into IZO, but decreased by 3% for the GIZO compound incorporating Ga into IZO in the visible region in comparison to that of IZO.

35.2: High‐Performance Solution‐Processed Oxide TFT with Dual Channel at Low Temperature

AbstractIn this study, we investigated solution‐processed oxide thin film transistors (TFTs) with dual channel (DC) at 350°C. The DC TFTs consisted of thin InZnO (IZO) channel and thick AlInZnO (AIZO) channel. The IZO could provide high carrier concentration to enhance the charge transport for high saturation mobility (μsat) and thick AIZO channel could also regulate the conductance for proper threshold voltage (Vth). The resistivity of front IZO thin films could be determined by composition ratio of In/Zn and thickness of IZO channel. Thus, we can demonstrate excellent device with μsat of 5.02 cm2/Vs, Vth of 0.35 V, and on/off ratio of over 106 at 350°C.

Improvement of bias stability of indium zinc oxide thin film transistors by the incorporation of hafnium fabricated by radio-frequency magnetron sputtering

We report on the fabrication and performance of amorphous oxide thin film transistors with indium zinc oxide (In 2O 3:ZnO = 1:1 mol%) and various ratios of hafnium-doped indium zinc oxide (IZO:HfO 2 = 2:0, 0.3, 0.7, and 1.1 mol%) deposited at the same deposition conditions for semiconductor channel layer. The carrier concentration ( N cp) of the HIZO films was further decreased from 7.08 × 10 17 to 5.0 × 10 16 cm − 3 . This indicates that Hf metal cations effectively suppress carrier generation due to the high electron negativity (1.3) of Hf. In addition, we compared bias instability of both devices after bias temperature stress (BTS) test under on-current state at V DS of 10 V and I DS of 3 μA at 60 °C for 420 min. It was found that the Hf metal cations could be effectively incorporated in the IZO thin films as a suppressor against both the oxygen deficiencies and the carrier generation in the ZnO-based system.

Effects of proton irradiation on indium zinc oxide-based thin-film transistors

In this research, we performed a high-dose proton-beam irradiation process to investigate the effect of irradiation on the performance of indium-doped zinc oxide-based thin-film transistors (IZO-TFTs) by controlling their electrical and structural properties. The resistivity of IZO thin films dramatically increased with increasing proton-irradiation doses up to ∼ 10 14 cm − 2, after which the resistivity recovered to a level similar to as-deposited IZO thin film. After proton irradiation, the crystallinity of IZO thin films was reduced due to defect-isolation and/or chemical-isolation. The field effect mobility of IZO-TFTs decreased from 2.20 cm 2 V − 1 s − 1 to 1.22 cm 2 V − 1 s − 1, turn-on voltage shifted −7 V to −21 V and subthreshold swing value increased after proton irradiation with a 10 12 cm − 2 dose. With proton-irradiation doses over 10 14 cm − 2, IZO-TFTs device performance recovered to a level similar to that of a pristine device. Moreover, irradiated thin films and devices have low sensitivities to post-thermal annealing due to the creation of antisite oxygen point defects.

High stability of amorphous hafnium-indium-zinc-oxide thin film transistor

Time dependence of the threshold voltage (Vth) shift in amorphous hafnium-indium-zinc oxide (a-HIZO) thin film transistor has been reported under on-current bias temperature stress measured at 60 °C. X-ray photoelectron spectroscopy results show the decrease in oxygen vacancies by Hf metal cations in a-HIZO systems after annealing process. High stability of a-HIZO systems has been observed due to low charge injection from the channel layer. Hf metal cations have been effectively incorporated into the IZO thin films as a suppressor against both the oxygen deficiencies and the carrier generation.

?Preparation of ITO and IZO thin films by using Facing Target Sputtering (FTS) method

In study, for transparent conductive oxides (TCOs) we investigated the electrical and the optical properties of thin films of indium oxide (In2O3) doped with 10 wt.% tin oxide (SnO2) and of indium oxide (In2O3) doped with 10 wt.% zinc oxide thin films in facing targets sputtering (FTS) system. All thin films were prepared on the glass at room temperature and at various oxygen contents in the sputter gas. All as-deposited thin films were annealed at various temperatures in an air atmosphere. The electrical and the optical properties of the as-deposited thin films were investigated by using a four point probe, an UV/VIS spectrometer, an X-ray diffractometer (XRD), and a Hall Effect measurement. As a result, with increasing oxygen content in the sputter gas, the optical transmittance in the visible range of all thin films increased (>80 %). ITO and IZO thin films had resistivities of 6.7 × 10−4 Ω·cm and 4.5 × 10−4 Ω·cm respectively at the optimum oxygen contents. After post-annealing, the structure of ITO thin film was polycrystalline, but the IZO thin films had amorphous.

The effect of indium doping on structural, electrical conductivity, photoconductivity and density of states properties of ZnO films

Abstract The effect of indium doping on structural, electrical conductivity, photoconductivity and density of states properties of IZO thin films has been investigated. X-rays diffraction spectra show that the IZO films are polycrystalline of wurtzite structure with preferential orientation of (0 0 2) direction. The IZO thin film for doping level of 2% exhibits the lowest resistivity of 6 × 10 −3 (Ω cm) compared to undoped ZnO of 17 (Ω cm). The optical gaps of the IZO thin films were determined using optical transmission spectra and the obtained optical band gap value increases slightly from 3.28 eV to 3.35 eV due to the indium doping. The IZO film indicates a strong photoconductivity with indium doping level. The density of states, traps concentration and relaxation time for the films were calculated using Laplace transform method and these parameters change with In doping level. It is evaluated that In doping has an important effect on the electronic and optical properties of ZnO thin films.

Modeling of In 2O 3-10 wt% ZnO thin film properties for transparent conductive oxide using neural networks

Effects of deposition process parameters on the deposition rate and the electrical properties of In 2O 3–10 wt% ZnO (IZO) thin films were modeled and analyzed by using the error back-propagation neural networks (BPNN). Output models were represented by response surface plots and the fitness of models was estimated by calculating the root mean square error (RMSE). The deposition rate of IZO thin films is affected by the RF power and the substrate temperature. The electrical properties of the IZO thin films are mainly controlled by O 2 ratio and the substrate temperature. The predicted output characteristics by BPNN can sufficiently explain the mechanism of IZO deposition process. Thus, neural network models can provide the reliable explanation of IZO film deposition.

Effect of Oxygen Concentration on Properties of Indium Zinc Oxide Thin Films for Flexible Dye-Sensitized Solar Cell

Indium zinc oxide (In2O3–ZnO, IZO) thin films were prepared with variation of oxygen concentration in Ar sputtering gas using rf magnetron sputtering system. Transmittance was greatly improved from 75 to 90% since surface roughness slightly decreased by adding oxygen and low resistivity of 3.28×10-4 Ω cm was achieved at 0.4% oxygen concentration. The performance of dye sensitized solar cell (DSSC) was also studied by fabricating cells with IZO thin films using UV/ozone treatment. According to the results, the efficiency was strongly affected by both transmittance and resistivity of IZO thin films deposited at different oxygen concentrations. Finally, the highest efficiency of 3.11% was achieved from IZO films deposited with 0.4% oxygen concentration, which exhibits a promising application of IZO thin films to flexible DSSC.

Physical properties of transparent conducting indium doped zinc oxide thin films deposited by pulsed DC magnetron sputtering

Transparent conducting In-doped (1at.%) zinc oxide (IZO) thin films are deposited on glass substrate by bipolar pulsed DC magnetron sputtering. We have investigated the effect of pulse frequency on the physical properties of the IZO films. A highly c-axis oriented IZO thin films were grown in perpendicular to the substrate. At optimal deposition conditions, IZO films with a smoothest surface roughness of ∼3.6 nm, a low-resistivity of 5.8 × 10−3 Ωcm, and a high mobility of 14 cm/Vs were achieved. The optical spectra showed a high transmittance of above 85% in the UV–visible region and exhibited the absorption edge of near 350 nm. In micro-Raman, we observed the three phonon modes of host ZnO, which are E 2 low, E 2 high, and A 1 modes, and the three additional modes. The origin of three additional modes is attributed to the host lattice defect due to the effect of In dopant and increasing the pulse frequency.

Organic Light-Emitting Devices with In-Doped (4 at. %) ZnO Thin Films as the Anodic Electrode

We have investigated transparent conducting properties of using In-doped (4 at. %) zinc oxide (IZO) thin films deposited on glass substrate by pulsed DC magnetron sputtering at low processing substrate temperatures. As increase of the substrate temperature, IZO thin films with better c-axis orientations were grown in perpendicular to the substrate and work functions of IZO films slightly decrease. The optical properties showed high transmittance of higher than 85% in the UV–visible region and exhibited the absorption edge of about 350 nm. The electrical properties exhibited the low resistivity of 1.1 ×10-3 Ω cm and the high mobility of ∼7.8 cm2 V-1 s-1. The organic light emitting diodes (OLEDs) with an IZO anode achieved a maximum luminance efficiency of 2.7 cd/A and external quantum efficiency of 0.47%, which are compared to the values of a control device fabricated on commercial ITO anode. These results indicate that IZO films hold promise for anodic electrodes in the OLEDs application.

Hydrogenated In-doped ZnO Thin Films for the New Anode Material of Organic Light Emitting Devices: Synthesis and Application Test

Transparent In-doped (1 at.%) zinc oxide (IZO) thin films are deposited by pulsed DC magnetron sputtering with H2 mixed Ar atmosphere on glass substrate without any heating process. Even at room temperature, highly c-axis oriented IZO thin films were grown in perpendicular to the substrate. The hydrogenated IZO (IZO:H) film isolated in H2 atmosphere for 30 min exhibited an average optical transmittance higher than 85% and low electrical resistivity of less than 2.7 × 10?3 Ω·cm. These values are comparable with those of commercially available ITO. Each of the IZO films was used as an anode contact to fabricate organic light-emitting diodes (OLEDs) and the device performances studied. At the current density of 1 × 103 A/m2, the OLEDs with IZO:H (H2) anode show excellent efficiency (11 V drive voltage) and a good brightness (8000 cd/m2) of the light emitted from the devices, which are as good as the control device built on a commercial ITO anode.

The Effects of SiO, SiON on IZO Thin Film Deposited by DCMG Method

The thin films of SiO and SiON were deposited individually by the inclination opposite target type DC magnetron sputtering equipment onto the glass substrate. And it was deposited IZO(In2O3 (90wt.%) + ZnO(10wt.%)) on those films. The effects of SiO and SiON were investigated on properties of IZO thin films. AFM images of IZO thin film included SiON film were shown smoother surfaces than that included SiO film. Multi layers of IZO were shown good properties because it have high transmissivity. Resistivity is in inverse proportion to Mobility. If it deposited SiO and SiON, generate layer of change between two layers(SiO or SiON + Substrate). Layer of change influenced resistance because Oxygen content was more than single layer of IZO. In case of using PET substrate, it influenced stronger than Glass substrate for rigid gas permeable and osmosis.

INFLUENCE OF THE SiO AND SiON BUFFER LAYER ON IZO THIN FILMS DEPOSITED ON PET BY INCLINATION OPPOSITE TARGET TYPE DC MAGNETRON SPUTTERING METHOD

IZO films were deposited onto polyethylene terephthalate (PET) substrate at room temperature by the inclination opposite target type DC magnetron sputtering equipment. In this paper, SiO or SiON thin films of about 20nm thickness were introduced as buffer layers between the IZO thin films and the PET substrate. Electrical resistivity, transmittance and surface uniformity properties were investigated. It is clear that the film surface roughness of multilayer thin films was less than that of IZO monolayer thin films. The surface average roughness ( Ra ) of the multilayer film with 230nm IZO layer thickness was about 1.6nm, and that of IZO monolayer film was 2.4nm. All of the multilayer samples had high optical transmittance (about 90%) in the visible region. Of particular note, the transmittance of multilayer films was slightly higher than that of monolayer films when the IZO layer was thicker than 200nm. High electrical conductivity was also achieved with thick films.

High optical quality IZO (In 2Zn 2O 5) thin films by PLD – A novel development for III–V opto-electronic devices

Extrinsic zinc oxide (heavily indium oxide doped), i.e., indium zinc oxide (In 2Zn 2O 5) (IZO) as novel transparent conducting oxide (TCO) thin films were grown by pulsed laser deposition (PLD) technique using Johnson Matthey “specpure” – grade 90% In 2O 3 mixed 10% ZnO (as commercial indium tin oxide (ITO) composition) pellets. The effects of substrate temperatures and heavy indium oxide incorporation on IZO thin film growth, optical transmission, absorption, reflection and photoluminescence were studied. As well as the feasibility of developing a novel high quality transparent oxide thin films was also studied simultaneously. Also, as a novelty merit we want to emphasize as a interesting physical effect that the average optical transmittance T% (max) ⩾95% of IZO thin films is rivals that of the most TCO films for this conductivity level (of the order of 10 3 Ω −1 cm −1). This is the first time that we have applied these PLD prepared IZO thin films to iso and hetero semiconductor–insulator–semiconductor (SIS) type solar cells as TCO coatings. The optical parameter values were calculated, diagrammatically enumerated and tabulated. From optical studies, we have observed that the films were act as highly anti-reflective (AR) coatings. From PL study, we have confirmed the purity and high electrical conductivity of the deposited thin films. Supplementary studies on surface, electrical, structural and internal morphology of thin film growth correlated with optical transmission, absorption, reflection and photoluminescence gives added advantages to this work.