Undoped Indium Oxide Films Research Articles

Sol Gel Dip Coated Yb and Tm Doped Indium Oxide Dye Sensitizrd Solar Cells

In2O3 thin films were deposited by the sol gel dip coating method adopting the following procedure. Clean ITO substrates were used for the deposition of the films. 10 ml of 0.33 M solution of Indium (III) nitrate was taken in a clean glass beaker. The solution was heated to 70˚C and the pH was brought to 9 by the addition of ammonia, then 1 gm of Acrylamide was added followed by the addition of 0.25 gm of N,N,bis methylene acrylamide. After 20 min, 5 mg ammonium persulphate initiator was added to this mixture. The solution became viscous. Cleaned microglass slides (2.5 cm x 7.5 cm) were immersed into the viscous solution and withdrawn at the rate of 1cm min-1. The film formed on the surface was dried in an air oven for about 15 min followed by annealing in air at different temperatures in the range of 350 - 500˚C for different durations in the range of 15 min to 90 min. Doping with Tm and Yb was done by adding 0.1 g of Yb(NO3)3 and 0.1 g of Tm(NO3)3 to the Indium nitrate solution before gelling. The doped and undoped films were dipped in N719 dye for 24 hours. a sandwich structure was formed by bonding the FTO substrate with dye coated In2O3 and a Pt counter electrode together through a hot-melt spacer, and a drop of electrolyte (0.60 M 1-butyl-3-methylimidazolium iodide (BMII), 0.03 M I2 was injected into the device through predrilled holes on the Pt counter electrode. DSSCs based on In2O3:Yb and In2O3:Tm were also fabricated via the same process. The XRD patterns of the In2O3, In2O3:Tm and In2O3:Yb. . All the patterns can be assigned to cubic phase standard card (JCPDS 06-0416) without any additional diffraction peaks. The UV–vis absorption spectra of the doped and undoped In2O3 exhibit the absorption peak of the pure In2O3 about 3.85 eV, which is consistent with the results published, and it icreases to 3.93 eV and 4.00 eV respectively as Tm and Yb are doped into In2O3. The J-V characteristics of the doped and undoped Indium oxide films indiacted that the Voc increased from 410 mV for undoped films increased to 530 mV and 630 mV for Tm and Yb doped films respectively. The Jsc increased from 2.45 mA cm-2 for the undoped films increased to 3.50 mA cm-2 and 4.25 mA cm-2 for Tm and Yb doping respectively.IPCE measurements indicated that for doped films the PCE was higher than that of undoped films. The fill factor of the films increased by doping with Tm and Yb. The larger Voc obtained with Yb doping can be explained on theb basis that the conduction band edge of Yb doped films is higher than that of undoped and Tm doped Indium oxide.

D ferromagnetism in undoped n and p-type In2O3 films

Undoped indium oxide films with room temperature d0 ferromagnetism were prepared by radiofrequency magnetron sputtering with different O2/Ar flux ratio. The optical and magnetic properties changed non-monotonously as the oxygen flux increases. A conversion of conductivity from n-type to p-type was observed as the flux ratio reached 15:15. The concordant results in structural, electrical, optical, and magnetic properties suggest that single ionized oxygen and indium vacancies play crucial roles in mediating the ferromagnetism in n and p-type In2O3 films, respectively.

Deposition of undoped indium oxide thin films on stripe-patterned substrates by spray CVD

Undoped indium oxide (In 2O 3) films were deposited on stripe-patterned Si substrates by an original spray chemical vapor deposition (spray CVD) using ethanol solution of indium (III) chloride. The step coverage of the films increased as the deposition temperature decreased. The grooves with 0.18 μm openings were successfully deposited at 253 °C. The step coverage of undoped indium oxide films were a similar tendency though resistivity of that showed the tendency opposite to the ITO film. Deposition mechanism of the undoped indium oxide films on stripe-patterned Si substrates was similar to that of the ITO films. The lowest resistivity of the films was 4.1×10 −3 Ω cm for the 260 nm-thick film deposited at 280 °C. The resistivity increased at higher temperature.

Doping-induced changes in the physical properties of In2O3:Sn films

Here we report studies carried out on heavily tin-doped and undoped indium oxide films. Structural, electronic transport and compositional properties of the sprayed films deposited with different doping levels of tin (0-110 at.% in solution), were investigated. X-ray diffraction, room-temperature Hall effect measurements, conductivity measurements at low temperatures and x-ray photoelectron spectroscopy were used for these studies. The films were polycrystalline and the preferred growth showed systematic changes with dopant incorporation from (400) to (222). The carrier mobility was very sensitive to these changes in orientation of preferred growth as well as the grain size. The high carrier concentration ( approximately 1020 cm-3) implied that the films belong to the class of degenerate semiconductors. Such a high carrier concentration was a result of increased non-stoichiometry and increased dopant incorporation. The conductivity measurements at low temperatures show that with increased Sn incorporation, electronic transport is governed by ionized impurity scattering and acoustic lattice scattering.

Properties of Low-Resistivity Undoped indium-Oxide Films Grown by Reactive Ion Plating and Electrochromic Tungsten-Oxide Films Grown by Electron-Beam Evaporation

AbstractThe use of gaseous discharge for ion plating and related techniques have been well known to improve coating properties in several ways. IN the arc-induced ion plating (AIIP), the ionization efficiency for the evaporants is so enhanced without any introduction of inert gases that the bias voltage for, and the temperature of the substrate are reduced in the preparation of the coatings. Highly transparent (> 90% transmission in the visible range) and highly conductive (resistivity ≅ 1.5 x 10-4 Ω cm) in-oxide films were deposited at a rate of 500 - 900 Å/min by aIIP of pure in in an O2 atmosphere of 10-4 Torr. Hall-effect measurement revealed that the observed low resistivity is due primarily to the excellent electron mobilty (≥ 70 cm2 / V sec) with carrier density up to 7 х 1020/cm3. Electrochromic WO3 films were also prepared and characterized.

Photoluminescence and electrical properties of erbium-doped indium oxide films prepared by rf sputtering

Erbium-doped indium oxide films were prepared by rf magnetron sputtering. The Er-doped oxide films are conducting (or semiconducting) with a resistivity in the range of 10−3–103 Ω cm, and are optically active, i.e., show a clear room-temperature photoluminescence at 1.54 μm, corresponding to intratransitions in Er3+ ions. Compared with the undoped indium oxide films, the erbium doping was found to have the effect of increasing the resistivity (up to two orders of magnitude) of the films, mainly via a reduction of carrier concentration. Postdeposition annealing in air ambient significantly enhances both the Er3+ luminescence and Hall mobility (up to 60 cm2/V s), and reduces the carrier concentration. Postdeposition annealing in reducing ambient (N2/H2), however, decreases the resistivity dramatically, mainly via an increase of carrier concentration (up to 1020 cm−3), and also enhances the Er3+ luminescence.

Erbium-doped indium oxide films prepared by radio frequency sputtering

Er doping of conducting oxide films has been investigated. Erbium-doped indium oxide films were prepared by rf magnetron sputtering. The deposited films were characterized in terms of electrical, optical, and structural properties. The Er-doped indium oxide films are highly (222)-oriented normal to the substrate surface and show a resistivity in the range of 10−3–103 Ω cm. The Er-doped conducting (or semiconducting) oxide films are optically active, i.e., show a clear room-temperature photoluminescence at 1.54 μm, corresponding to intratransitions in Er3+ ions. Compared with the undoped indium oxide films, the erbium doping is found to have the effect of increasing the resistivity (up to two orders of magnitude) of the films, mainly via a reduction of carrier concentration. Post-deposition annealing in air ambient significantly enhances both the Er3+ luminescence and Hall mobility (up to 60 cm2/V s), and reduces the carrier concentration. The enhancement of Hall mobility is attributed to a reduction of grain boundaries and voids with the anneal treatment as supported by the x-ray diffraction measurement results. Post-deposition annealing in reducing ambient (N2/H2) decreases the resistivity dramatically, mainly via an increase of carrier concentration (up to 1020 cm−3), and also enhances the Er3+ luminescence.

Dependence of structural, electrical and optical properties of undoped indium oxide films on thickness

For highly conducting transparent films, thickness is an important parameter. This investigation optimizes the film thickness to obtain high electrical conductivity without appreciably affecting the transparency. Undoped Indium oxide films having different thickness have been deposited on Corning glass (7059) by using the spray pyrolysis technique. Study of the structural, electrical and optical properties of these films reveals that the mobility increases as the film thickness increases till its value is 6500 A° after which the mobility decreases. This behaviour of the mobility is closely related to the crystallinity of the films. A high value of mobility of 53 cm 2V −1s −1 has been achieved. The variation in the number of charge carriers with thickness is small. At 6500 A° the lowest value of resistivity obtained is 9.3 × 10 −4щ cm and the visible transmission is 82 %. Another interesting feature of this work is the improvement in both electrical and optical film properties for the thickest film (1.03 μm) when the substrate temperature is increased from 425°C to 475°C.

Thickness dependence of electrical properties in thin films of undoped indium oxide prepared by ion-beam sputtering

Preparation and electrical characterization of undoped indium oxide films were examined as a function of thickness and annealing. Thin films ranging from 1.1 to 113 nm thickness were deposited on glass substrates by ion-beam sputtering. Low-angle X-ray diffraction analysis in multi-layered films showed the possibility that physically continuous and almost flat films were formed even in the thinnest 1.1 nm films. Room temperature resistivity of as-deposited films decreased sharply by more than five orders of magnitude as the thickness increased from 1.1 to 5.2 nm. The 2.4 nm thick films, in its as-deposited state, showed a gradual resistivity modulation with the change of atmosphere between air and argon gas at room temperature. Annealing at 300° C for 5 h in air increased the resistivity drastically; the room temperature resistivity of 24.3 nm thick films changed from 2.2×10−3 Ω cm (as-deposited) to higher than ∼ 105 Ω cm (annealed).

Highly conducting transparent undoped indium oxide films deposited below 100°C by activated reactive evaporation

Highly transparent and conducting undoped indium oxide films have been obtained with a resistivity of ≈;4 × 10−1 Ωcm, a carrier density of ≈; × 1020 cm−3 and a mobility of ≈;18 cm2 V−1−1 at a substrate temperature <70° C and a deposition rate of ≈;8 A/s by an activated reactive evaporation process. The stability of electrical and optical properties at room temperature in the open air is reasonable for a film optimized for conductivity. The optical bandgap of these films is ≈;3.3 eV, lower than that of a high temperature deposited tin doped indium oxide film. It is found that undoped indium oxide films with the best conductivity cannot be obtained if a threshold temperature of ≈;200° C is exceeded either during deposition or during post deposition vacuum anneals. However, highly conductive tin doped indium oxide can be easily obtained at high temperature (T ≈; 400° C) by activated reactive evaporation. It is also noted that highly conductive tin doped indium oxide films are more difficult to make at the lower end of the temperature range unless certain precautions are taken.