On the structural and electrical characteristics of zinc oxide thin films

ZnO thin films with thickness d = 100 nm were deposited by radio frequency magnetron sputtering onto glass substrate from different targets. The structural analyses of the films indicate they are polycrystalline and have a wurtzite (hexagonal) structure. Crystallites are preferentially oriented with (002) plane parallel to the substrate surface and the samples have low values for surface roughness, between 1.7 nm and 2.7 nm. The mechanism of electrical conduction in the studied films is strongly influenced by this polycrystalline structure and we used Van der Pauw method to analyze these properties. Electrical studies indicate that the ZnO thin films are n-type. For the cooling process, thermal activation energy of electrical conduction of the samples can vary from 1.22 eV to 1.07 eV (for the ZnO layer obtained from for metallic Zn target) and from 0.90 eV to 0.63 eV (for the ZnO layer obtained from ZnO target), respectively. The influence of deposition arrangement and oxidation conditions on the structural and electrical properties of the ZnO films was investigated in detail.     

Influence of thickness and growth temperature on the optical and electrical properties of ZnO thin films

Zinc oxide transparent conductive thin films were prepared using the pulsed laser deposition technique onto Corning glass substrates and the dependences of their optical and electrical properties on the thickness and the growth temperature were investigated. As shown, the films present 90% average transmittance, their energy gap position depending on the film thickness and the growth temperature. An additional absorption band was also observed near 3.44 eV, the position of its maximum also depending on the growth parameters. Finally, the electrical properties of the films were found to be affected mainly by the growth temperature and less by the thickness.     

DC electrical conduction of zinc telluride thin films

Zinc telluride (ZnTe) thin films were deposited by thermal evaporation onto glass substrates kept at room temperature. X-ray diffraction studies showed that the films were polycrystalline and of cubic structure. The current-voltage (I-V) characteristics of the Au/ZnTe/Au thin film sandwich system at different temperatures were studied. The DC conduction was explained using the Schottky or Jonscher-Ansari modified Pool-Frenkel mechanism.     

Preparation of aluminum doped zinc oxide films and the study of their microstructure, electrical and optical properties

Aluminum doped zinc oxide (AZO) polycrystalline thin films were prepared by sol-gel dip-coating process on optical glass substrates. Zinc acetate solutions of 0.5 M in isopropanol stabilized by diethanolamine and doped with a concentrated solution of aluminum nitrate in ethanol were used. The content of aluminum in the sol was varied from 1 to 3 at.%. Crystalline ZnO thin films were obtained following an annealing process at temperatures between 300 °C and 500 °C for 1 h. The coatings have been characterized by X-ray diffraction, UV-Visible spectrophotometry, scanning electron microscopy, and electrical resistance measurement. The ZnO:Al thin films are transparent (∼ 90%) in near ultraviolet and visible regions. With the annealing temperature increasing from 300 °C to 500 °C, the film was oriented more preferentially along the (0 0 2) direction, the grain size of the film increased, the transmittance also became higher and the electrical resistivity decreased. The X-ray diffraction analysis revealed single-phase ZnO hexagonal wurtzite structure. The best conductors were obtained for the AZO films containing 1 at.% of Al, annealed at 500 °C, 780 nm film thickness.     

Dc conductivity of consolidated nanoparticles of zinc sulfide

Abstract

Zinc sulfide nanoparticles with average grain sizes ranging from 3 to 12 nm were prepared by arrested chemical preparation, followed by suitable thermal processing. The size of the grains was determined by x-ray line broadening. Dc measurement was performed on compacts of nanoparticles using a Keithley electrometer in the temperature range of 313–423 K. The dc conductivity, σ_dc, of our samples is much higher than that of ZnS single crystals; σ_dc increases with a decrease in the grain size.     

Influence of lithium doping on the structural and electrical characteristics of ZnO thin films

Thin films of undoped and lithium-doped Zinc oxide, (Zn_1 − xLi_x)O; x = 0, 0.05, 0.10 and 0.20 were prepared by sol-gel method using spin-coating technique on silicon substrates [(111)Pt/Ti/SiO₂/Si)]. The influence of lithium doping on the structural, electrical and microstructural characteristics have been investigated by means of X-ray diffraction, leakage current, piezoelectric measurements and scanning electron microscopy. The resistivity of the ZnO film is found to increase markedly with low levels (x ≤ 0.05) of lithium doping thereby enhancing their piezoelectric applications. The transverse piezoelectric coefficient, e₃₁^? has been determined for the thin films having the composition (Zn_0.95Li_0.05)O, to study their suitability for piezoelectric applications.     

水溶液中组装碳纳米管/硫化锌纳米晶复合膜

半导体材料ZnS在光催化领域具有重要的应用前景，如何提高其光催化能力仍是目前关键问题之一。应用碳纳米管的独特结构和性能有望调变和改善ZnS的催化功能。采用一种简便的方法在水溶液中成功组装了硫化锌／碳纳米管纳米晶颗粒（ZnS／CNTs）复合膜。TEM显示纳米复合膜以CNTs组装成席状骨架，ZnS纳米晶填充在CNTs间的缝隙或者包裹在CNTs的表面，二者之间存在良好的接触和相互作用。生成的ZnS纳米颗粒尺寸均匀、大小约为5nm。用EDS、SAED和XRD分析了复合膜的元素组成以及ZnS的晶相结构。结果显示ZnS纳米晶为闪锌矿结构。     

高性能导电薄膜的制备

采用磁控溅射法在玻璃基底上制备了Cr-Cu-Al-Cr薄膜,用焊接法测试薄膜附着性能,用x射线衍射仪（XRD）、原子力显微镜（AFM）和台阶仪对薄膜进行表征,研究溅射过程中以及在高温大气环境下薄膜的防氧化方法,分析薄膜晶粒大小与电性能关系,制备出性能较好的导电膜。     

Properties of nanocrystalline zinc oxide thin films prepared by thermal decomposition of electrodeposited zinc peroxide

Zinc peroxide thin films were electrodeposited from aqueous solution at room temperature using H₂O₂ as the oxidation agent. Nanocrystalline zinc oxide thin films were then obtained from thermal decomposition of zinc peroxide thin films. The grain sizes of ZnO through thermal decomposition of ZnO₂ at 200 °C, 300 °C and 400 °C were estimated from the peak width of ZnO(110) obtained from X-ray diffraction and were 6.3 nm, 9.1 nm and 12.9 nm, respectively. The optical properties of zinc oxide thin films have been studied. The photoluminescence results indicate that ZnO thin films have low Stokes blue shift (about 110 meV) and low oxygen vacancies.     

Role of precursors on morphology and optical properties of ZnS thin films prepared by chemical spray pyrolysis

This study investigates the effect of different growth parameters on the structural and optical properties of ZnS thin films, prepared using spray pyrolysis. The films were prepared using different Zn:S ratios (between 1:1 and 1:6) and in different growth solutions: (A), zinc chloride and thiourea and (B) dehydrated zinc acetate and thiourea, both in distilled water.By varying the Zn:S ratio in the films, the optical properties (absorption and photoluminescence) show that different species are created during film growth. This was deduced from the wide emission band appearing in the green region of the photoluminescence spectra, and from the change in band gap, which varies between 3.2 and 3.5 eV. Films formed from solution (A) with a Zn:S ratio of 1:3 or 1:4 show the best morphology and transmission. ZnS has a wider band gap than other conventional II-VI semiconductors utilized in various electronic and optical devices and can be expected to provide a useful window layer of solar cells which leads to an improvement in overall efficiency by decreasing absorption loss.     

Structural, optical, and electrical properties of tin sulfide thin films grown by spray pyrolysis

Tin sulfide (SnS) thin films have been prepared by spray pyrolysis (SP) technique using tin chloride and N, N-dimethylthiourea as precursor compounds. Thin films prepared at different temperatures have been characterized using several techniques. X-ray diffraction studies have shown that substrate temperature (T_s) affects the crystalline structure of the deposited material as well as the optoelectronic properties. The calculated optical band gap (E_g) value for films deposited at T_s = 320-396 °C was 1.70 eV (SnS). Additional phases of SnS₂ at 455 °C and SnO₂ at 488 °C were formed. The measured electrical resistivity value for SnS films was ∼ 1 × 10⁴ Ω-cm.     

Structural and electrical properties of sputtered indium-zinc oxide thin films

In this study, indium-zinc oxide (IZO) thin films have been prepared at a room temperature, 200 and 300 °C by radio frequency magnetron sputtering from a In₂O₃-12 wt.% ZnO sintered ceramic target, and their dependence of electrical and structural properties on the oxygen content in sputter gas, the substrate temperature and the post-heat treatment was investigated. X-ray diffraction measurements showed that amorphous IZO films were formed at room temperature (RT) regardless of oxygen content in sputter gas, and micro-crystalline and In₂O₃-oriented crystalline films were obtained at 200 and 300 °C, respectively. From the analysis on the electrical and the structural properties of annealed IZO films under Ar atmosphere at 200, 300, 400 and 500 °C, it was shown that oxygen content in sputter gas is a critical parameter that determines the local structure of amorphous IZO film, stability of amorphous phase as well as its eventual crystalline structure, which again decide the electrical properties of the IZO films. As-prepared amorphous IZO film deposited at RT gave specific resistivity as low as 4.48 × 10^− 4 Ω cm, and the highest mobility value amounting to 47 cm²/V s was obtained from amorphous IZO film which was deposited in 0.5% oxygen content in sputter gas and subsequently annealed at 400 °C in Ar atmosphere.     

Absorption and photocurrent properties of thin ZnS films formed by pulsed-laser deposition on quartz

The absorption and photocurrent properties of thin film ZnS on quartz glass formed by pulsed-laser deposition have been studied experimentally and theoretically at room temperature. Using the Lorentzian function to describe the exciton density of states, we show that the absorption is strongly influenced by excitonic formation. The theory for the absorption, however, does not describe the PC spectra of the film since the exciton remains electrically neutral up to fields of 1 kV/cm due to the high binding energy of 36 meV. Therefore, the fundamental absorption according to density of states and Urbach rule determines the shape of the photocurrent spectrum.     

Low-cost and reliable thin film encapsulation for organic light emitting diodes using magnesium fluoride and zinc sulfide

We report highly efficient gas diffusion barriers for organic light emitting diodes (OLEDs) with an encapsulation structure composed of alternating magnesium fluoride (MgF₂) and zinc sulfide (ZnS) layers grown by vacuum thermal deposition. The half lifetime of yellow OLEDs under an initial luminance of 2000 cd/m² with rubrene as an emitter reached 245 h using three pairs of MgF₂/ZnS layers. The device lifetime was obviously improved using MgF₂ and ZnS as passivation layers before UV-cured epoxy seal without desiccant with the lifetime for the initial luminance dropping to 56% being over 500 h. This simple and inexpensive encapsulation method can potentially be applied to top-emitting OLEDs due to good light transmission characteristic of the passivation film.     

Preparation and electrical/optical bistable property of potassium tetracyanoquinodimethane thin films

Potassium tetracyanoquinodimethane (K(TCNQ)) thin films were prepared using physical vapor deposition combined with solid state chemical replacement reaction. Reversible electrical bistable behavior at or even above room temperature was observed; and, the optical bistable property of K(TCNQ) film was observed.     

Cadmium sulfide nanotubes thin films: Characterization and photoelectrochemical behavior

Monodisperse cadmium sulfide nanotubes (CdS NTs) with a diameter of 100 nm were synthesized on indium-doped tin oxide glass substrates using chemical bath deposition and self-sacrificial template technique. This CdS thin film was characterized by transmission electron microscope, scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis spectrophotometer. This film gave a short circuit photocurrent of 4.4 mA/cm², an open circuit photovoltage of 0.75 V, a fill factor of 0.49, and an overall conversion efficiency of 1.29% under a simulated solar illumination of 100 mW/cm². All these photoelectrochemical properties of the films were dependent on the microstructure of the nanotubes and the thickness of the film. A facile and efficient way to prepare CdS-based photoelectrodes for photoelectrochemical cells was provided in this report.     

Preparation and characterization of amorphous manganese sulfide thin films by SILAR method

Manganese sulfide thin films were deposited by a simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method using manganese acetate as a manganese and sodium sulfide as sulfide ion sources, respectively. Manganese sulfide films were characterized for their structural, surface morphological and optical properties by means of X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and optical absorption measurement techniques. The as-deposited film on glass substrate was amorphous. The optical band gap of the film was found to be thickness dependent. As thickness increases optical band gap was found to be increase. The water angle contact was found to be 34°, suggesting hydrophilic nature of manganese sulfide thin films. The presence of Mn and S in thin film was confirmed by energy dispersive X-ray analysis.     

Preparation and gas-sensing characteristics of nanocrystalline spinel zinc ferrite thin films

Zinc ferrite is a promising sensor material. In this paper, thin films of nanocrystalline zinc ferrite were deposited on alumina substrates by nebulization of a 0.01-M solution of a mixture of ZnCl/sub 2/ and FeCl/sub 3/ in ethanol (Zn:Fe=1:2) followed by pyrolysis and annealing in flowing air. The resulting films were characterized by X-ray diffraction and scanning electron microscopy, and the gas-sensing properties of as-deposited films were also investigated.     

Photovoltaic structures using chemically deposited tin sulfide thin films

Chemically deposited thin films of tin sulfide forms in two crystalline structures depending on the bath compositions used: orthorhombic, SnS(OR), and zinc-blende, SnS(ZB). These films posses p-type electrical conductivity and have band gaps of 1.2 and 1.7 eV, respectively. The photovoltaic structure: SnO₂:F/CdS/SnS(ZB)/SnS(OR) with evaporated Ag-electrode reported here shows an open circuit voltage (V_OC) of 370 mV, a short circuit current density (J_SC) of 1.23 mA/cm², fill factor of 0.44 and conversion efficiency of 0.2% under 1 kW/m² illumination intensity. We present an evaluation for improvement in the light generated current density when the two types of SnS absorber films are used. Different evaporated electrode materials were tested, from which Ag-electrode was chosen for this work. The results given above were obtained with SnS(ZB) film of 0.1 µm and SnS(OR) film of 0.5 µm in thickness.     

Effect of alumina doping on structural, electrical, and optical properties of sputtered ZnO thin films

A systematic study of the influence of alumina (Al₂O₃) doping on the optical, electrical, and structural characteristics of sputtered ZnO thin films is reported in this study. The ZnO thin films were prepared on 1737F Corning glass substrates by R.F. magnetron sputtering from a ZnO target mixed with Al₂O₃ of 0-4 wt.%. X-ray diffraction (XRD) analysis demonstrates that the ZnO thin films with Al₂O₃ of 0-4 wt.% have a highly (002) preferred orientation with only one intense diffraction peak with a full width at half maximum (FWHM) less than 0.5°. The electrical properties of the Al₂O₃-doped ZnO thin films appear to be strongly dependent on the Al₂O₃ concentration. The resistivity of the films decreases from 74 Ω·cm to 2.2 × 10^− 3 Ω·cm as the Al₂O₃ content increases from 0 to 4 wt.%. The optical transmittance of the Al₂O₃-doped ZnO thin films is studied as a function of wavelength in the range 200-800 nm. It exhibits high transparency in the visible-NIR wavelength region with some interference fringes and sharp ultraviolet absorption edges. The optical bandgap of the Al₂O₃-doped ZnO thin films show a short-wavelength shift with increasing of Al₂O₃ content.