Search

Pulsed DC magnetron sputtering was used to deposit indium‑tin-oxide (ITO) thin films on glass substrates for application in photovoltaic devices as the final window layer. The evolution of crystal phase, morphology, resistivity and transmittance of the ITO films under different thermal annealing procedure ( in - situ annealing versus post-annealing) at relatively low temperatures (up to 300 °C) were studied. Fully crystalline ITO films with low sheet resistance of 24 Ω/□ and high average transmittance (exclude glass substrate) of 90.10% with a Haacke's figure of merit 1.47 × 10 − 2 Ω − 1 were obtained by in - situ annealing at 200 °C. In comparison, the minimum temperature observed to fully crystalize the ITO thin films with competitive crystallinity, electrical and optical properties by post-annealing was 250 °C. The corresponding post-annealed 300 nm thick films showed sheet resistance of 49 Ω/□ and average transmittance (exclude glass substrate) as high as 91.93% with a Haacke's figure of merit 0.882 × 10 − 2 Ω − 1 . The surface morphology of the as-deposited ITO films remained homogeneous after post-annealing whereas large particles (up to 100 nm) were observed on the surface of the films deposited by in - situ annealing. The results indicated that different thermal treatment procedures at lower temperatures produce significant effect on the electrical, optical and other physical properties of the ITO thin films which are critical for the window layer in photovoltaics. [ABSTRACT FROM AUTHOR]

The strategic metal indium is recovered from solutions containing tin and lead that are typical of those obtained from leach solutions of metal component fractions of electronic waste including the leach solutions from indium tin oxide thin film conductive layers that contain only indium and tin. Almost total recovery of the metals can be achieved from nitric, perchloric and acetic acid leach solutions using a novel cylindrical mesh electrode electrolysis cell under appropriate conditions. The optimum separation of indium from tin and lead is achieved by a novel three-stage process from nitric acid media in the presence of SCN − as a complexing agent. Lead is removed from dilute indium-tin-lead solutions in the first stage from 0.1 mol L −1 nitric acid solution by electrodeposition over an 8 h period in the absence of SCN − to give a residual solution containing a maximum of 2 mg L −1 of lead (97% recovery). Tin is removed in the second stage by electrodeposition over an 8 h period from the solution after addition of 0.02 mol L −1 SCN − to give a maximum residual electrolyte tin concentration of 3 mg L −1 (94% recovery). In the third stage indium is recovered at the anode of the cylindrical mesh electrode cell as an oxy-hydroxide phase by increasing the SCN − concentration to 0.1 mol L −1 and carrying out the electrolysis for a period of 24 h to give a residual solution containing 1 mg L −1 of indium (98% recovery). [ABSTRACT FROM AUTHOR]

Abstract: Indium tin oxide (ITO) thin films, produced by electron beam evaporation technique onto quartz substrates maintained at room temperature, are grown as nanofibers. The dependence of structural and optical properties of ITO thin films on the film thickness (99–662nm) has been reported. The crystal structure and morphology of the films are investigated by X-ray diffraction and scanning electron microscope techniques, respectively. The particle size is found to increase with increasing film thickness without changing the preferred orientation along (222) direction. The optical properties of the films are investigated in terms of the measurements of the transmittance and reflectance determined at the normal incidence of the light in the wavelength range (250–2500nm). The absorption coefficient and refractive index are calculated and the related optical parameters are evaluated. The optical band gap is found to decrease with the increase of the film thickness, whereas the refractive index is found to increase. The optical dielectric constant and the ratio of the free carrier concentration to its effective mass are estimated for the films. [Copyright &y& Elsevier]

Abstract: Thin films of indium tin oxide (ITO) sputter-deposited by dc-plasma containing deuterium on glass substrate without any heat treatments exhibited gradual lowering in electrical resistivity with increasing the deuterium content [D2] in plasma gas by 1% and then demonstrated a jump in resistivity by further increase of [D2] than 1%. X-ray photoelectron spectroscopy revealed that hydroxyl-bonded oxygen in ITO grew continuingly with [D2]. Deuterium positioned at the interstitial site increased almost quantitatively with increasing [D2]. Rutherford backscattering spectroscopy showed gradual reduction in the oxygen content of ITO with increasing [D2] by 1% and then demonstrated an abrupt increase of the oxygen content with the increase of [D2] than 1%. The films with [D2]<1% were oxygen deficient, but those with [D2]>1% were excess of oxygen. The most oxygen deficient film of [D2]=1% was the most conductive. Behavior in the resistivity with [D2] looks parallel to that in the oxygen content. A lower resistivity of the films corresponded well to oxygen vacancy rather than hydrogen interstitial. [Copyright &y& Elsevier]

Bottom gate, top contact thin‐film transistors (TFTs) with transparent Sn‐doped zinc oxide as the active layer have been fabricated on glass substrate at room temperature. Indium tin oxide, alumni zinc oxide (AZO) and Al thin films serve as the source/drain (S/D) electrode. It turns out that devices with AZO S/D electrodes exhibit preferable properties such as a saturation mobility of 13.6 cm2/Vs, a subthreshold slope of 381 mV/decade, a Vth of 3.47 V and an on/off current ratio of 3.1 × 107. Moreover, the superior output characteristic and lower parasitic resistance demonstrate the excellent contact performance of the tin‐zinc oxide TFTs with AZO S/D electrodes. [ABSTRACT FROM AUTHOR]

Abstract: Float glass substrates covered by high quality ITO thin films (Balzers) were subjected for an hour to single thermal treatments at different temperature between 100°C and 600°C. In order to study the electric and optical properties of both annealed and not annealed ITO-covered float glasses, ellipsometry, spectrophotometry, impedance analysis, and X-ray measurements were performed. Moreover, variable angle spectroscopic ellipsometry provides relevant information on the electronic and optical properties of the samples. ITO film is modeled as a dense lower layer and a surface roughness layer. The estimated optical density for ITO and the optical density of the surface roughness ITO layer increases with the annealing temperature. In the near-IR range, the extinction coefficient decreases while the maximum of the absorption in the near UV range shift towards low photon energy as the annealing temperature increases. Spectrophotometry was used to estimate the optical band-gap energy of the samples. The thermal annealing changes strongly the structural and optical properties of ITO thin films, because during the thermal processes, the ITO thin film absorbs oxygen from air. This oxygen absorption decreases the oxygen vacancies therefore the defect densities in the crystalline structure of the ITO thin films also decrease, as confirmed both by ellipsometry and X-ray measurements. [Copyright &y& Elsevier]

A ceramic thermocouple based on indium-tin-oxide (ITO) thin films is being developed to measure the surface temperature of gas turbine engine components employed in power and propulsion systems that operate at temperatures in excess of 1500°C. By fabricating ITO elements with substantially different charge carrier concentrations, it was possible to construct a robust ceramic thermocouple. A thermoelectric power of 6.0 μV/°C, over the temperature range 25-1250°C, was realized for an unoptimized ITO ceramic thermocouple. The charge carrier concentration difference in the legs of the ITO thermocouple was established by r.f. sputtering in oxygen-rich and nitrogen-rich plasmas. SEM micrographs revealed that after high-temperature exposure, the surfaces of the nitrogen prepared ITO films exhibited a partially sintered microstructure with a contiguous network of ITO nanoparticles. Thermal cycling of ITO films in various oxygen partial pressures showed that the temperature coefficient of resistance was nearly independent of oxygen partial pressure at temperatures above 800°C and eventually became independent of oxygen partial pressure after repeated thermal cycling below 800°C. Based on these results, a versatile ceramic sensor system has been envisioned where a ceramic thermocouple and strain sensor can be combined to yield a multifunctional ceramic sensor array. [ABSTRACT FROM PUBLISHER]

Radio frequency (rf)-sputtered indium tin oxide (ITO) thin films were characterized by studying their structure, electrical and optical properties. Before characterization the ITO films were annealed at different temperatures ranging from 100 to 500 °C for a constant time of 15 min in air. The ITO thin films were observed to possess a cubic structure with (1 1 0) texture, an electrical resistivity in the range (5–11.5)×10−4 Ω cm at different annealing temperatures. The rise in resistivity due to annealing was associated with the filling up of oxygen vacancies, and the fall in resistivity was attributed to the rearrangement and removal of defects as well as improvement in the crystalline nature of these films. The optical bandgap energy was found to be &ap;4.0 eV. The ITO thin films were of comparable quality to those deposited elsewhere for use as window layers in solar cells. [Copyright &y& Elsevier]