Characterization of Zn<Subscript>2</Subscript>SnO<Subscript>4</Subscript> Thin Films Prepared by RF Magnetron Sputtering

Zn₂SnO₄ (ZTO) is a stable semiconductor in ZnO–SnO₂ system and important transparent conducting oxide (TCO) predominantly used in optoelectronic devices. ZTO thin films were prepared by RF magnetron sputtering using Zn₂SnO₄ ceramic target in this paper. The effects of annealing temperatures and oxygen contents on characterization of ZTO thin films were studied. The results show that ZTO thin films prepared by RF magnetron sputtering are amorphous with an optical band gap of 3.22 eV. After annealing at 650°C in Ar atmosphere for 40 min, ZTO films possess a spinel structure with an optical band gap of 3.62 eV. The atomic force microscope (AFM) data of morphology reveals that the surface roughness of films is about 2 nm. The results of energy dispersive spectrometer (EDS) show that the concentration ratio of Zn to Sn is in the range from 1.44 to 1.57. The results of Hall-effect-measurement system reveal that the resistivity of films varies from 102 to 10–1 Ωcm, carrier concentration is about 10¹⁷ cm^–3, and mobility ranges from 10⁰ to 10¹ cm² v^–1 s^–1.     

Change of the oxidation state of phosphorus in sputtered Li3±xPO4±y and Li3±xPO4±yNz films

Thin Li_3±xPO_4±yN_zLi⁺- electrolyte films prepared by reactive rf-magnetron sputtering of Li₃PO₄ incorporate a certain amount of nitrogen which is made responsible for increased Li⁺-conductivity as well as at least kinetic stability with lithium metal. A possible change of the oxidation state +5 of phosphorus as a result of the sputter process has not yet been considered for explanation. We have found out that it cannot be generally assumed that reactive low power rf-magnetron sputtering of Li₃PO₄ results in fully oxidized films, even when pure O₂ is employed as sputtering gas. Our films immediately react with H₂O releasing a garlic smelling gas. The reaction area is surrounded by a white crust afterwards. CuSO₄ and AgNO₃ aqueous solutions become reduced. Impedance measurements yield an ionic conductivity of 2·10⁻⁶ S/cm at 25 °C and an activation energy of 0.62 eV.     

Characterization and electrical behavior of new lithium chalcoborate thin films

Thin films obtained with glasses of the B₂S₃Li₂S and B₂S₃Li₂SLiI systems, using a vacuum evaporation technique have been investigated. In each system, amorphous thin films and starting glasses have the same composition and similar conductivities, about 10^?4 and 10^?3Ω^?1cm^?1 respectively at 25°C. The deposition rate was in both cases 140 Å s^?1. However, a thermal treatment at 90°C of the thin films containing lithium iodide enhances the conductivity by a factor of 10 and leads to lower activation energy (0.18 eV). This behavior has been identified as a Phipps effect and can be attributed to a quick ion diffusion along thin film - substrate interface. This interfacial region was found to show unique conduction properties including a very low Li⁺ migration enthalpy.     

Aluminum-assisted crystallization and <Emphasis Type="Italic">p</Emphasis>-type doping of polycrystalline Si

Aluminum-doped p-type polycrystalline silicon thin films have been synthesized on glass substrates using an aluminum target in a reactive SiH₄+Ar+H₂ gas mixture at a low substrate temperature of 300 °C through inductively coupled plasma-assisted RF magnetron sputtering. In this process, it is possible to simultaneously co-deposit Si–Al in one layer for crystallization of amorphous silicon, in contrast to the conventional techniques where alternating metal and amorphous Si layers are deposited. The effect of aluminum target power on the structural and electrical properties of polycrystalline Si films is analyzed by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and Hall-effect analysis. It is shown that at an aluminum target power of 100 W, the polycrystalline Si film features a high crystalline fraction of 91%, a vertically aligned columnar structure, a sheet resistance of 20.2 kΩ/□ and a hole concentration of 6.3×10¹⁸ cm⁻³. The underlying mechanism for achieving the semiconductor-quality polycrystalline silicon thin films at a low substrate temperature of 300 °C is proposed.     

Optimization of magnetron deposition process for formation of high-quality oriented ZnO films

The thickness distribution and structure of ZnO films deposited by DC-magnetron sputtering of a zinc target in argon-oxygen gaseous medium at substrate temperature of 27°C and gas pressure in the chamber within 5×10^?3 ? 5×10^?2 mm Hg was investigated. It was revealed that the use of a target with a certain depression in the sputtering zone allows depositing high quality c-oriented films at lower gas pressure than with a flat target. The dependence of film quality on geometric factors is interpreted on the basis of theoretical computations with the assumption that the film structure is improved when the flux of deposited Zn particles decreases while their energy increases.     

Structural and electrical properties of fluorine-doped zinc tin oxide thin films prepared by radio-frequency magnetron sputtering

Transparent and conductive thin films of fluorine doped zinc tin oxide (FZTO) were deposited on glass substrates by radio-frequency (RF) magnetron sputtering using a 30 wt% ZnO with 70 wt% SnO₂ ceramic targets. The F-doping was carried out by introducing a mixed gas of pure Ar, CF₄, and O₂ forming gas into the sputtering chamber while sputtering ZTO target. The effect of annealing temperature on the structural, electrical and optical performances of FZTO thin films has been studied. FZTO thin film annealed at 600 °C shows the decrease in resistivity 5.47 × 10⁻³ Ω cm, carrier concentration ∼10¹⁹ cm⁻³, mobility ∼20 cm² V⁻¹ s⁻¹ and an increase in optical band gap from 3.41 to 3.60 eV with increasing the annealing temperatures which is well explained by Burstein–Moss effect. The optical transmittance of FZTO films was higher than 80% in all specimens. Work function (ϕ) of the FZTO films increase from 3.80 eV to 4.10 eV through annealing and are largely dependent on the amounts of incorporated F. FZTO is a possible potential transparent conducting oxide (TCO) alternative for application in optoelectronics.     

Li4GeO4-Zn2GeO4赝二元系相图的研究

本文用差热分析和X射线衍射的方法对Li₄GeO₄-Zn₂GeO₄赝二元系相图进行了研究。结果指出,文献中所报道的锂离子导体Li₁₄Zn(GeO₄)₄不是化合物,而是含Zn₂GeO₄的以Li₄GeO₄为基的固溶体,由于Zn₂GeO₄的加入,使Li₄GeO₄的高温相稳定存在于室温。根据研究结果,提出了关于Li₁₄Zn(GeO₄)₄多晶陶瓮样品在室温长期放置后,电导率明显降低的解释。     

Structural, electrical, and optical properties of ZnInO alloy thin films

Indium zinc oxide (IZO) thin films with different percentages of In content (In/[In+Zn]) are synthesized on glass substrates by magnetron sputtering, and the structural, electrical and optical properties of IZO thin films deposited at different In₂O₃ target powers are investigated. IZO thin films grown at different In₂O₃ target sputtering powers show evident morphological variation and different grain sizes. As the In₂O₃ sputtering power rises, the grain size becomes larger and electrical mobility increases. The film grown with an In₂O₃ target power of 100 W displays the highest electrical mobility of 13.5 cm·V^-1·s^-1 and the lowest resistivity of 2.4 × 10^-3 Ω·cm. The average optical transmittance of the IZO thin film in the visible region reaches 80% and the band gap broadens with the increase of In₂O₃ target power, which is attributed to the increase in carrier concentration and is in accordance with Burstein-Moss shift theory.     

Li4SiO4-Li3VO4赝二元系和Li4GeO4-Li4SiO4-Li3VO4赝三元系中新的锂离子导体

本文在室温到300℃的温度范围内研究了Li₄SiO₄-Li₃VO₄和Li₄GeO₄-Li₄SiO₄-Li₃VO₄体系中的离子导电性,发现γ_II相固溶体Li_3+xV_1-xSi_xO₄是好的锂离子导体。所研究的成分中Li_3.3V_0.7Si_0.3O₄的离子电导率最高,室温下为1×10^-5Ω^-1·cm^-1,在42—192℃的电导激活能为0.36eV,电子电导率可以忽略,因而这是迄今所发现的最好的锂离子导体之一。粗略确定了Li₄GeO₄-Li₄SiO₄-Li₃VO₄三元系中电导率高的范围,发现在Li_3.5V_0.5Ge_0.5O₄中Si部分取代Ge可以使电导率进一步提高,Li_3.5V_0.5Ge_0.4Si_0.1O₄的室温电导率可达1.3×10^-5Ω^-1·cm^-1,电导激活能为0.40eV。 关键词：     

Electron microprobe compositional analysis of sputtered tantalum-aluminium films

In the present paper the methods for measurement of the composition of two or more component tantalum-based thin sputtered films are summarized. The influence of the target construction on the composition of the films is discussed. The Ta-Al films were sputtered from composite Ta-Al targets. The composition of films was measured by means of the electron microprobe technique. From results it follows that using the composite targets for sputtering in argon at a pressure of 2×10^?2 torr and in its mixture with nitrogen (10^?3 torr), the composition of Ta-Al films is proportional to the ratio of the Ta and Al exposed surfaces on the target. The proportionality factor equals to the ratio of “effective” sputtering yields of target components measured at given sputtering conditions. The presence of nitrogen in sputtering gas decreases the value of Ta yield 2.2 times. If a small Al surface is sputtered together with much larger Ta surface, the sputtering yield of Al remains unchanged. In Ta-Al films the occluded argon was qualitatively determined. The presence of nitrogen was not proved. This seems to be caused by the absorption of nitrogen characteristic radiation in the investigated films.     

Raman study of WO3 thin films

The influence of substrates, thermal treatment and coloration-bleaching cycles on the structure of WO₃ thin films used in electrochromic devices has been investigated by Raman microscopy. Films (2000–8000 Å) were prepared by RF sputtering from a metallic tungsten target at a constant pressure (5 × 10^?3Torr) of pure oxygen or a mixture of Ar20% O₂. They are amorphous, transparent and electrochromic. Thermal treatment at 360°C produces crystallization. Modifications of the WO₃ framework are also induced by coloration-bleaching cycles.     

Room-temperature epitaxial growth of CeO2(001) films on YSZ buffered Si(001) substrates

2 (001) epitaxial thin films deposited on Si(001) with yttria-stabilized zirconia buffers have been obtained for the first time at room temperature by pulsed-laser deposition. The influence of oxygen pressure on the crystal quality of CeO₂ was studied for the films deposited at 100 °C. The rocking curve full width at half maximum of the CeO₂(002) peak for films deposited at room temperature and 100 °C was between 1° and 2°, for oxygen pressures below 3×10^-2 mbar. The best crystal quality was obtained at around 3×10^-3 mbar. Epitaxial growth at room temperature was confirmed by cross-sectional transmission electron microscopy. Scanning electron microscopy and atomic force microscopy revealed very smooth surfaces for oxygen pressure below 3×10^-2 mbar, with rms roughness values around 0.3 nm over 5 μm×5 μm. Received: 25 September 1997/Accepted: 22 April 1998     

Optical and mechanical properties of AlF3 films produced by pulse magnetron sputtering of Al targets with CF4/O2 gas

In this study, AlF₃ thin films were deposited by pulse magnetron sputtering of Al targets with different ratios of CF₄/O₂ gas and at different sputtering powers. The optical and mechanical properties of the AlF₃ thin films were analyzed. The transmittance spectra showed no obvious negative inhomogeneous refractive indices. Denser films with a low optical absorption were obtained when high sputtering powers were used (larger than 30 W). The lowest extinction coefficient (7.3 × 10⁻⁴ at 193 nm) of the films can be reached with 12 sccm O₂ flow rate and at 160W sputtering power. All of the residual stresses were compressive and their trends were consistent with the refractive indices. The lowest compressive stress (0.068 GPa) was obtained when the AlF₃ films were prepared at 160W sputtering power.     

Li+ ion conducting γ solid solutions in the systems Li4XO4-Li3YO4: X=Si,Ge, Ti; Y=P,As, V; Li4XO4-LiZO2: Z=Al,Ga, Cr and Li4GeO4-Li2CaGeO4

A wide variety of solid solutions with a structure related to that of γ Li₃PO₄ may be prepared. These include materials such as lisicon, Li_2+2xZn_1-xGeO₄ and the title systems, many of which have not been studied previously. Conductivity data are presented for eight systems: Li₄GeO₄-Li₃(P, As, V)O₄; Li₄TiO₄-Li₃(As, V)O₄; Li₄GeO₄-Li(Ga, Al)O₂; Li₄GeO₄-Li₂CaGeO₄ and the results compared with those reported in the literature for Li₄SiO₄-Li₃(P, As, V)O₄ systems and lisicon. dc polarisation measurements were made on four of the system and it was found that the electronic transference number is 10^?4 or less. The materials with the highest conductivity were found in the systems, Li₄ (Ge, Ti) O₄-Li₃ (As, V)O₄ with σ ~ (3 to 4) × 10^?5 Ω^?1 cm^?1 at room temperature. It is noted that the systems with the highest conductivity are generally those with the largest unit cell volume.     

Ionic transport in the lithium nitride bromides,Li6NBr3 and Li1 3N4Br

The ionic and electronic conductivities of the lithium nitride bromides Li₆NBr₃ and Li_{1 3}N₄Br have been studied in the temperature range from 50 to 220°C and 120 to 450°C, respectively. Both compounds are practically pure lithium ion conductors with negligible electronic contribution. Li₆NBr₃ has an ionic conductivity Ω of 2 × 10^-6Ω^-1cm^-1 at 100°C and an activation enthalpy for σT of 0.46 eV. Li_{1 3}N₄Br shows a phase transition at about 230°C. The activation enthalpy for σT is 0.73 eV below and 0.47 eV above this temperature. The conductivities at 150 and 300°C were found to be 3.5 × 10^-6 Ω^-1cm^-1 and 1.4 × 10^-3Ω^-1cm^-1, respectively. The crystal structure is hexagonal at room temperature with $\text{a = 7.415 (1)}\text{A}\text{?}$ and $\text{c = 3.865 (1)}\text{A}\text{?}$.     

Temperature and frequency dependence of the ferroelectric characteristics of BaTiO<Subscript>3</Subscript> thin films for nonvolatile memory applications

Ferroelectric thin films of BaTiO₃ were successfully deposited on SiO₂/Si substrate under the optimal rf magnetron sputtering conditions, and their electrical and ferroelectric characteristics were discussed. The memory window, capacitance, threshold voltage and leakage current density of MFIS structure under different frequencies and temperatures were also reported. The variations of ferroelectric capacitance and threshold voltage would be attributed to the as-deposited BaTiO₃ films of MFIS structure as the temperature and frequency increased. Besides, the memory window, threshold voltage and leakage current density would be degraded from 4 V, 5 V and 8×10^-10 A/cm² to 2.5 V, 10 V and 5×10^-4 A/cm², respectively, as the temperature increased from 25 to 90 °C. PACS 77.84.-s; 81.15.Cd; 73.40.Qv; 51.50.+v; 67.80.Gb     

Bi-Sb-Te基热电薄膜温差电池离子束溅射制备与表征

本文采用离子束溅射Bi/Te和Sb/Te二元复合靶,直接制备n型Bi₂Te₃热电薄膜和p型Sb₂Te₃热电薄膜.在退火时间同为1 h的条件下,对所制备的Bi₂Te₃薄膜和Sb₂Te₃薄膜进行不同温度的退火处理,并对其热电性能进行表征.结果表明,在退火温度为150 ℃时,制备的n型Bi₂Te₃关键词： 薄膜温差电池 2Te₃薄膜')" href="#">Sb₂Te₃薄膜 2Te₃薄膜')" href="#">Bi₂Te₃薄膜 离子束溅射     

Dielectric anomaly in Li-doped zinc oxide thin films grown by sol–gel route

Sol–gel route was employed to grow polycrystalline thin films of Li-doped ZnO thin films (Zn_1-xLi_xO, x=0.15). Polycrystalline films were obtained at a growth temperature of 400–500 °C. Ferroelectricity in Zn_0.85Li_0.15O was verified by examining the temperature variation of the real and imaginary parts of dielectric constant, and from the C–V measurements. The phase transition temperature was found to be 330 K. The room-temperature dielectric constant and dissipation factor were 15.5 and 0.09 respectively, at a frequency of 100 kHz. The films exhibited well-defined hysteresis loop, and the values of spontaneous polarization (P_s) and coercive field were 0.15 μC/cm² and 20 kV/cm, respectively, confirming the presence of ferroelectricity. PACS 77.22Ch; 77.22Ej; 77.80Bh     

Ultra‐thin (002)‐oriented Al‐doped zinc oxide transparent electrode grown on oxygen‐controlled homo‐seed layer

Highly (002)‐oriented Al‐doped zinc oxide (AZO) thin films with the thickness of less than 200 nm have been deposited on an oxygen‐controlled homo‐seed layer at 200 °C by DC magnetron sputtering. With the homo‐seed layer being employed, the full‐width at half maximum (FWHM) of the (002) diffraction peak for the AZO ultra‐thin films decreased from 0.33° to 0.22°, and, the corresponding average grain size increased from 26.8 nm to 43.0 nm. The XRD rocking curves revealed that the AZO ultra‐thin film grown on the seed layer deposited in atmosphere of O₂/Ar of 0.09 exhibited the most excellent structural order. The AZO ultra‐thin film with homo‐seed layer reached a resistivity of 4.2 × 10^–4 Ω cm, carrier concentration of 5.2 × 10²⁰ cm^–3 and mobility of 28.8 cm² V^–1 s^–1. The average transmittance of the AZO ultra‐thin film with homo‐seed layer reached 85.4% in the range of 380–780 nm including the substrate. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Monolithic electrochromic devices using lithium ion conducting perovskite-type oxides

The electrical conductivities of several perovskite-type lithium ion conductors in the Li-Sr-Nb-Ta-Ti-O system have been investigated. The Li⁺-ion conductivities of the Ta-compounds were found to be higher than those of the corresponding Nb-compounds, i.e., Li_0.3Sr_0.6Ta_0.5Ti_0.5O₃ exhibits a bulk ionic conductivity of 1.7×10⁻⁴ S/cm at 30 °C, while Li_0.3Sr_0.6Nb_0.5Ti_0.5O₃ shows a value of 5.4×10⁻⁶ S/cm at the same temperature. Substitution of Fe in Li_0.3Sr_0.6Ta_0.5Ti_0.5O₃ decreases the Li⁺-ion conductivity slightly. The operation of a monolithic (single element) electrochromic devices was demonstrated using perovskite-type Li_0.3Sr_0.6B_0.5Ti_0.5O₃ (B=Nb, Ta). The tantalum compound exhibited the largest coloration at the positive electrode side by the application of a voltage of 1.5 V and was bleached under short-circuit conditions at 350 °C. Paper presented at the 9th EuroConference on Ionics, Ixia, Rhodes, Greece, Sept. 15–21, 2002.