Deposition of Al doped ZnO thin films on the different substrates with radio frequency magnetron sputtering
TL;DR: In this article, the physical properties of transparent and conductive Al-Zn alloy thin films were investigated using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM).
Abstract: This work focuses on fabrication, characterization and understanding of the physical properties of transparent and conductive Al–Zn alloy thin films. Films were deposited onto glass slides, polyethylene terephthalate (PET) and silicon by radio-frequency (RF) reactive magnetron sputtering technique, using Al–Zn alloy targets. In order to generate oxidation process of Al–Zn alloys, Ar:O2 gas mixing in (5:5) ratio was used. Transmittances, reflectance, refractive index and thicknesses of AZO films were measured by UV–Vis spectrophotometry and interferometry respectively. Crystallographic properties were investigated by X-ray diffraction (XRD) method. Surface morphologies of produced films were characterized by atomic force microscopy (AFM) and also field emission scanning electron microscopy (FESEM).
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TL;DR: In this article, Tauc plots are fitted to a simple expression in which the intercept gives the band-gap and the fitting exponent identifies the electronic transition as direct or indirect (see Tauc et al., Phys. Status Solidi 15, 627 (1966); these are often called “Tauc” plots).
Abstract: One of the most frequently used methods for characterizing thin films is UV–Vis absorption. The near-edge region can be fitted to a simple expression in which the intercept gives the band-gap and the fitting exponent identifies the electronic transition as direct or indirect (see Tauc et al., Phys. Status Solidi 15, 627 (1966); these are often called “Tauc” plots). While the technique is powerful and simple, the accuracy of the fitted band-gap result is seldom stated or known. We tackle this question by refitting a large number of Tauc plots from the literature and look for trends. Nominally pure zinc oxide (ZnO) was chosen as a material with limited intrinsic deviation from stoichiometry and which has been widely studied. Our examination of the band gap values and their distribution leads to a discussion of some experimental factors that can bias the data and lead to either smaller or larger apparent values than would be expected. Finally, an easily evaluated figure-of-merit is defined that may help guide more accurate Tauc fitting. For samples with relatively sharper Tauc plot shapes, the population yields Eg(ZnO) as 3.276 ± 0.033 eV, in good agreement with data for single crystalline material.
765 citations
Cites methods from "Deposition of Al doped ZnO thin fil..."
...Numerous deposition methods are available for zinc oxide thin films including solgel[24-29], chemical vapor deposition [9, 18, 30, 31], hydrothermal [32, 33] or solvothermal growth[34], magnetron sputtering[35-38] and pulsed laser deposition (PLD)[39-42]....
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TL;DR: In this article, the reproducibility of Tauc plot slopes for ZnO as a model direct-gap material and compare these experimental values with the theoretically derived slope was examined. But the experimental slope values varied by several orders of magnitude.
Abstract: One of the most frequently used methods for characterizing thin films is UV–Vis absorption. The near-edge region can be fitted to a simple expression where the intercept gives the band gap and the fitting exponent identifies the electronic transition as direct or indirect. [See Tauc et al., Physica Status Solidi 15, 627 (1966); naturally, these are usually called “Tauc” plots.] In earlier work, we found that direct band gaps fitted using Tauc's method can be quite accurate, to ∼1% [see Viezbicke et al., Phys. Status Solidi B 252, 1700 (2015)]. Still, slopes of these Tauc plots are less frequently quantified, even though the slopes are directly rooted in key band-structure parameters. In this study, we examine the reproducibility of Tauc plot slopes for ZnO as a model direct-gap material and compare these experimental values with the theoretically derived slope. In contrast to the band gap accuracy, the experimental slope values varied by several orders of magnitude. The histogram of slope values was significantly more compact for Tauc plots exhibiting less Urbach tail contribution. In these cases, the Tauc slopes can provide an order-of-magnitude quantification of other key band characteristics such as carrier effective mass.
164 citations
TL;DR: In this paper, ZnO thin films were deposited on glass substrates by reactive RF magnetron sputtering method at argon-oxygen gas mixing (1:1) atmosphere.
44 citations
TL;DR: In this paper, the correlation of the doping level of Al and Ga on doped ZnO films was revealed in order to investigate the structural, morphology, optical transmittance, and electronic properties of the films.
42 citations
01 Nov 2019-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this paper, the impact of ion species and high energy photons irradiation on structured ZnO nanowires (ZnO-NWs) and at different ion energies (keV to MeV), ion fluences, and substrate temperatures are discussed.
Abstract: It is a misunderstanding that higher energy ion irradiation on nanomaterials has only detrimental effects on their properties. Recent research reveals that higher energy irradiation on nanostructure materials is favorable with advantageous effects. Light, medium, heavy ions, and high energy photons serve as a veritable tool to synthesized nanowires for these effects. In this article, experimental research on the impact of ion species and high energy photons irradiation on structured ZnO nanowires (ZnO-NWs) and at different ion energies (keV to MeV), ion fluences, and substrate temperatures are discussed. The study has revealed that ZnO-NWs structures were damaged at high irradiation fluence under room temperature. Moreover, the porous structures of ZnO-NWs are created by light ions irradiation at a higher temperature. It is noteworthy that the effect of these irradiation beams induced-cutting of ZnO-NWs and fabrication of nano-holes in ZnO-NWs valuable for nano-devices in space technology under harsh environment.
31 citations
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TL;DR: A novel semiconducting material is proposed—namely, a transparent amorphous oxide semiconductor from the In-Ga-Zn-O system (a-IGZO)—for the active channel in transparent thin-film transistors (TTFTs), which are fabricated on polyethylene terephthalate sheets and exhibit saturation mobilities and device characteristics are stable during repetitive bending of the TTFT sheet.
Abstract: Transparent electronic devices formed on flexible substrates are expected to meet emerging technological demands where silicon-based electronics cannot provide a solution. Examples of active flexible applications include paper displays and wearable computers1. So far, mainly flexible devices based on hydrogenated amorphous silicon (a-Si:H)2,3,4,5 and organic semiconductors2,6,7,8,9,10 have been investigated. However, the performance of these devices has been insufficient for use as transistors in practical computers and current-driven organic light-emitting diode displays. Fabricating high-performance devices is challenging, owing to a trade-off between processing temperature and device performance. Here, we propose to solve this problem by using a novel semiconducting material—namely, a transparent amorphous oxide semiconductor from the In-Ga-Zn-O system (a-IGZO)—for the active channel in transparent thin-film transistors (TTFTs). The a-IGZO is deposited on polyethylene terephthalate at room temperature and exhibits Hall effect mobilities exceeding 10 cm2 V-1 s-1, which is an order of magnitude larger than for hydrogenated amorphous silicon. TTFTs fabricated on polyethylene terephthalate sheets exhibit saturation mobilities of 6–9 cm2 V-1 s-1, and device characteristics are stable during repetitive bending of the TTFT sheet.
7,301 citations
TL;DR: In this paper, the authors present a comprehensive and up-to-date description of the deposition techniques, electro-optical properties, solid state physics of the electron transport and optical effects and some applications of these transparent conductors.
2,553 citations
TL;DR: In this paper, optical transitions occur between localized states below the mobility edge and extended states of the opposite band, and they are associated with localized states in the band gap, where the authors interpret the results in terms of a model in which optical transitions are interpreted by a Gaussian distribution.
Abstract: Optical absorption measurements near the absorption edge are presented for three bulk semiconductor glasses: ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$, ${\mathrm{Ge}}_{33}$${\mathrm{As}}_{12}$${\mathrm{Se}}_{55}$, and ${\mathrm{Ge}}_{28}$${\mathrm{Sb}}_{12}$${\mathrm{Se}}_{60}$. The weak absorption tails observed below the exponential part of the edge also follow an exponential law, and they are not due to a light-scattering artifact. We associate them with localized states in the band gap. The results are interpreted in terms of a model in which optical transitions occur between localized states below the mobility edge and extended states of the opposite band.
1,157 citations
TL;DR: In this article, transparent thin-film transistors (TTFTs) with an amorphous zinc tin oxide channel layer formed via rf magnetron sputter deposition are demonstrated.
Abstract: Transparent thin-film transistors (TTFTs) with an amorphous zinc tin oxide channel layer formed via rf magnetron sputter deposition are demonstrated. Field-effect mobilities of 5–15 and 20–50cm2V−1s−1 are obtained for devices post-deposition annealed at 300 and 600°C, respectively. TTFTs processed at 300 and 600°C yield devices with turn-on voltage of 0–15 and −5–5V, respectively. Under both processing conditions, a drain current on-to-off ratio greater than 107 is obtained. Zinc tin oxide is one example of a new class of high performance TTFT channel materials involving amorphous oxides composed of heavy-metal cations with (n−1)d10ns0 (n⩾4) electronic configurations.
778 citations
TL;DR: In this article, aluminum-doped zinc oxide films have been deposited on soda lime glass substrates from diethyl zinc, triethyl aluminum, and ethanol by atmospheric pressure chemical-vapor deposition in the temperature range 367-444°C.
Abstract: Aluminum‐doped zinc oxide films have been deposited on soda lime glass substrates from diethyl zinc, triethyl aluminum, and ethanol by atmospheric pressure chemical‐vapor deposition in the temperature range 367–444 °C. Film roughness was controlled by the deposition temperature and the dopant concentration. The films have resistivities as low as 3.0 × 10−4 Ω cm, infrared reflectances close to 90%, visible transmissions of 85%, and visible absorptions of 5.0% for a sheet resistance of 4.0 Ω/⧠. The aluminum concentration within doped films measured by electron microprobe is between 0.3 and 1.2 at. %. The electron concentration determined from Hall coefficient measurements is between 2.0 × 1020 and 8.0 × 1020 cm−3, which is in agreement with the estimates from the plasma wavelength. The Hall mobility, obtained from the measured Hall coefficient and dc resistivity, is between 10.0 and 35.0 cm2/V s. Over 90% of the aluminum atoms in the film are electrically active as electron donors. Scanning electron microscopy and x‐ray diffraction show that the films are crystalline with disklike structures of diameter 100–1000 nm and height 30–60 nm. The films have the desired electrical and optical properties for applications in solar cell technology and energy efficient windows.
592 citations