Exploring negative ion behaviors and their influence on properties of DC magnetron sputtered ITO films under varied power and pressure conditions

We deposited indium-tin-oxide(ITO)films on silicon and quartz substrates by magnetron sputtering technology in pure argon.Using electrostatic quadrupole plasma diagnostic technology,we investigate the effects of discharge power and discharge pressure on the ion flux and energy distribution function of incidence on the substrate surface,with special attention to the production of high-energy negative oxygen ions,and elucidate the mechanism behind its production.At the same time,the structure and properties of ITO films are systematically characterized to understand the potential effects of high energy oxygen ions on the growth of ITO films.Combining with the kinetic property analysis of sputtering damage mechanism of transparent conductive oxide(TCO)thin films,this study provides valuable physical understanding of optimization of TCO thin film deposition process.

Properties of Reactive Magnetron Sputtered ITO Films without in-situ Substrate Heating and Post-deposition Annealing

Indium tin oxide (ITO) films were prepared on polyester, Si and glass substrate with relatively high deposition rate of above 0.9 nm/s by DC reactive magnetron sputtering technique at the sputtering pressure of 0.06 Pa system, respectively. The dependence of resistivity on deposition parameters, such as deposition rate, target-to-substrate distance (TSD), oxygen flow rate and sputtering time (thickness), has been investigated, together with the structural and the optical properties. It was revealed that all ITO films exhibited lattice expansion. The resistivity of ITO thin films shows significant substrate effect: much lower resistivity and broader process window have been reproducibly achieved for the deposition of ITO films onto polyester rather than those prepared on both Si and glass substrates. The films with resistivity of as low as 4.23 x 10^-4 Ω.cm and average transmittance of ～78% at wavelength of 400～700 nm have been achieved for the films on polyester at room temperature.

Study on adhesion and electro-optical properties of ITO films on flexible PET substrate

High-quality ITO films on flexible PET substrate were prepared by RF magnetron sputtering at low deposition temperature with different Ar gas sputtering pressure.Adhesion and electro-optical properties of ITO films were investigated as a function of Ar partial pressure.The sputtering conditions provide very uniform ITO films with high transparency(>85%in 400-760 nm spectra)and low electrical resistivity(1.408×10^(-3)-1.956×10^(-3)Ω·cm).Scratch test experiments indicate that there is a good adhesion property between ITO films and PET substrate,the critical characteristic load increases from 16.5 to 23.2 N with increasing Ar sputtering pressure from 0.2 to 1.4 Pa.

Tuning optical properties of ITO films grown by rf sputtering:Effects of oblique angle deposition and thermal annealing

Indium tin oxide(ITO)thin films were prepared using the technique of rf-sputtering with oblique angle deposition(OAD).The films were as-deposited and thermally treated at 250℃.The combination of substrate inclination and annealing was used for modifying morphological and structural properties that lead to changes of the optical properties.The resulting films show morphology of tilted nanocolumn,fissures among columns,and structural changes.The as-deposited films are structurally disordered with an amorphous component and the annealed films are crystallized and more ordered and the film diffractograms correspond to the cubic structure of In2O3.The refractive index could be modified up to 0.3 in as-deposited films and up to 0.15 in annealed films as functions of the inclination angle of the nanocolumns.Similarly,the band gap energy increases up to about 0.4 eV due to the reduction of the microstrain distribution.It is found that the microstrain distribution,which is related to lattice distortions,defects and the presence of fissures in the films,is the main feature that can be engineered through morphological modifications for achieving the adjustment of the optical properties.

Effects of power on ion behaviors in radio-frequency magnetron sputtering of indium tin oxide(ITO)

This study delves into ion behavior at the substrate position within RF magnetron discharges utilizing an indium tin oxide(ITO)target.The positive ion energies exhibit an upward trajectory with increasing RF power,attributed to heightened plasma potential and initial emergent energy.Simultaneously,the positive ion flux escalates owing to amplified sputtering rates and electron density.Conversely,negative ions exhibit broad ion energy distribution functions(IEDFs)characterized by multiple peaks.These patterns are clarified by a combination of radiofrequency oscillation of cathode voltage and plasma potential,alongside ion transport time.This elucidation finds validation in a one-dimensional model encompassing the initial ion energy.At higher RF power,negative ions surpassing 100 e V escalate in both flux and energy,posing a potential risk of sputtering damages to ITO layers.

Periodic transparent nanowires in ITO film fabricated via femtosecond laser direct writing

This paper reports the fabrication of regular large-area laser-induced periodic surface structures(LIPSSs)in indium tin oxide(ITO)films via femtosecond laser direct writing focused by a cylindrical lens.The regular LIPSSs exhibited good properties as nanowires,with a resistivity almost equal to that of the initial ITO film.By changing the laser fluence,the nanowire resistances could be tuned from 15 to 73 kΩ/mm with a consistency of±10%.Furthermore,the average transmittance of the ITO films with regular LIPSSs in the range of 1200-2000 nm was improved from 21%to 60%.The regular LIPSS is promising for transparent electrodes of nano-optoelectronic devices-particularly in the near-infrared band.

High-performance omnidirectional self-powered photodetector constructed by CsSnBr_(3)/ITO heterostructure film

Omnidirectional photodetectors attract enormous attention due to their prominent roles in optical tracking systems and omnidirectional cameras.However,it is still a challenge for the construction of high-performance omnidirectional photodetectors where the incident light can be effectively absorbed in multiple directions and the photo-generated carriers can be effectively collected.Here,a high-performance omnidirectional self-powered photodetector based on the CsSnBr_(3)/indium tin oxide(ITO)heterostructure film was designed and demonstrated.The as-fabricated photodetector exhibited an excellent self-powered photodetection performance,showing responsivity and detectivity up to 35.1 mA/W and 1.82×10^(10) Jones,respectively,along with the smart rise/decay response time of 4 ms/9 ms.Benefitting from the excellent photoelectric properties of the CsSnBr_(3) film as well as the ability of the CsSnBr_(3)/ITO heterostructure to efficiently separate and collect photo-generated carriers,the as-fabricated photodetector also exhibited an excellent omnidirectional self-powered photodetection performance.All the results have certified that this work finds an efficient way to realize high-performance omnidirectional self-powered photodetectors.

Indium–tin oxide films obtained by DC magnetron sputtering for improved Si heterojunction solar cell applications

The indium-tin oxide （ITO） film as the antireflection layer and front electrodes is of key importance to obtaining high efficiency Si heterojunction （HJ） solar cells. To obtain high transmittance and low resistivity ITO films by direct-current （DC） magnetron sputtering, we studied the impacts of the ITO film deposition conditions, such as the oxygen flow rate, pressure, and sputter power, on the electrical and optical properties of the ITO films. ITO films of resistivity of 4 x 10-4 ~.m and average transmittance of 89% in the wavelength range of 380-780 nm were obtained under the optimized conditions： oxygen flow rate of 0.1 sccm, pressure of 0.8 Pa, and sputtering power of 110 W. These ITO films were used to fabricate the single-side HJ solar cell without an intrinsic a-Si：H layer. However, the best HJ solar cell was fabricated with a lower sputtering power of 95 W, which had an efficiency of 11.47%, an open circuit voltage （Voc） of 0.626 V, a filling factor （FF） of 0.50, and a short circuit current density （Jsc） of 36.4 mA/cm2. The decrease in the performance of the solar cell fabricated with high sputtering power of 110 W is attributed to the ion bombardment to the emitter. The Voc was improved to 0.673 V when a 5 nm thick intrinsic a-Si：H layer was inserted between the （p） a-Si：H and （n） c-Si layer. The higher Voc of 0.673 V for the single-side HJ solar cell implies the excellent c-Si surface passivation by a-Si：H.

Finite Element Analysis for Temperature Compensation of ITO Conductive Film System

Indium tin oxide(ITO)heating film is primarily used as the defogging component of an instrument observation window.Conventionally,a constant current is used to heat the film.Through the feedback of the temperature sensing component,the output current is adjusted to achieve a set temperature.However,the temperature of the heating film is nonuniformly distributed,and determining the correct output current is time-consuming.This study adopted finite element heat transfer analysis to determine a heating method(such as heat power and heat flux)for an ITO conductive heating film system.The results of the analysis may serve as a reference for temperature compensation in ITO conductive heating films.

A new DRIE cut-off material in SOG MEMS process

The silicon on glasses process is a common preparation method of micro-electro-mechanical system inertial devices,which can realize the processing of thick silicon structures.This paper proposes that indium tin oxides(ITO)film can serve as a deep silicon etching cut-off layer because ITO is less damaged under the attack of fluoride ions.ITO has good electrical conductivity and can absorb fluoride ions for silicon etching and reduce the reflection of fluoride ions,thus reducing the foot effect.The removal and release of ITO use an acidic solution,which does not damage the silicon structure.Therefore,the selection of the sacrificial layer has an excellent effect in maintaining the shape of the MEMS structure.This method is used in the preparation of MEMS accelerometers with a structure thickness of 100μm and a feature size of 4μm.The over-etching of the bottom of the silicon structure caused by the foot effect is negligible.The difference between the simulated value and the designed value of the device characteristic frequency is less than 5%.This indicates that ITO is an excellent deep silicon etch stopper material.

Thickness dependency of nonlinear optical properties in ITO/Sn composite films

In this study,a batch of indium tin oxide(ITO)/Sn composites with different ratios was obtained based on the principle of thermal evaporation by an electron beam.The crystalline structure,surface shape,and optical characterization of the films were researched using an X-ray diffractometer,an atomic force microscope,a UV-Vis-NIR dual-beam spectrophotometer,and an open-hole Z-scan system.By varying the relative thickness ratio of the ITO/Sn bilayer film,tunable nonlinear optical properties were achieved.The nonlinear saturation absorption coefficientβmaximum of the ITO/Sn composites is−10.5×10^(−7)cm/W,approximately 21 and 1.72 times more enhanced compared to monolayer ITO and Sn,respectively.Moreover,the improvement of the sample nonlinear performance was verified using finite-difference in temporal domain simulations.

Effect of Ga_2O_3 buffer layer thickness on the properties of Cu/ITO thin films deposited on flexible substrates

Cu and Cu/ITO films were prepared on polyethylene terephthalate （PET） substrates with a Ga2O3 buffer layer using radio frequency （RF） and direct current （DC） magnetron sputtering. The effect of Cu layer thickness on the optical and electrical properties of the Cu film deposited on a PET substrate with a Ga2O3 buffer layer was studied, and an appropriate Cu layer thickness of 4.2 nm was obtained. Changes in the optoelectrical properties of Cu（4.2 nm）/ITO（30 nm） films were investigated with respect to the Ga2O3 buffer layer thickness. The optical and electrical properties of the Cu/ITO films were significantly influenced by the thickness of the Ga2O3 buffer layer. A maximum transmission of 86%, sheet resistance of 45 Ω/□ and figure of merit of 3.96 × 10^-3 Ω^ -1 were achieved for Cu（4.2 nm）/ITO（30 nm） films with a Ga2O3 layer thickness of 15 nm.

Photoelectric properties of ITO thin films deposited by DC magnetron sputtering

As anti-reflecting thin films and transparent electrodes of solar cells, indium tin oxide （ITO） thin films were prepared on glass substrates by DC magnetron sputtering process. The main sputtering conditions were sputtering power, substrate temperature and work pressure. The influence of the above sputtering conditions on the transmittance and conductivity of the deposited ITO films was investigated. The experimental results show that, the transmittance and the resistivity decrease as the sputtering power increases from 30 to 90 W. When the substrate temperature increases from 25 to 150℃, the transmittance increases slightly whereas the resistivity decreases. As the work pressure increases from 0.4 to 2.0 Pa, the transmittance decreases and the resistivity increases. When the sputtering power, substrate temperature and work pressure are 30 W, 150℃, 0.4 Pa respectively, the ITO thin films exhibit good electrical and optical properties, with resistivity below 10^-4 Ωcm and the transmittance in the visible wave band beyond 80%. Therefore, the ITO thin films are suitable as transparent electrodes of solar cells.

Soft chemistry based sponge-like indium tin oxide a prospective component of photoanode for solar cell application

Previously we reported the synthesis of novel organic-inorganic compo- site indium tin oxide （ITO） foam precursor leading to the formation of ＂sponge-like＂ ITO by burning away the organics, This newly made sponge-like ITO possesses relatively high electrical conductivity due to phonon confinement with reasonable pore structure and may have potential application as functional materials in semiconducting dye absorbing layer in dye-sensitized solar cell （DSSC） and also as the receptor of electrons injected from the quantum dots （QDs） of organic-inorganic hybrid QD based solar cell. This report is a short review of ＂sponge-like＂ ITO described as a lecture note on its future use as an alternative new prospective material for photoanode of solar cell in the domain of sustainable energy,