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Rock-salt CdZnO as a transparent conductive oxide
摘要： Transparent conducting oxides (TCOs) are widely used in applications from solar cells to light emitting diodes. Here, we show that the metal organic chemical vapor deposition (MOCVD)-grown, rock-salt CdZnO ternary, has excellent potential as a TCO. To assess this compound, we use a combination of infrared reflectance and ultraviolet-visible absorption spectroscopies, together with Hall effect, to determine its optical and electrical transport characteristics. It is found that the incorporation of Zn produces an increment of the electron concentration and mobility, yielding lower resistivities than those of CdO, with a minimum of 1:96 (cid:2) 10(cid:3)4 X (cid:4) cm for a Zn content of 10%. Moreover, due to a combination of increasing bandgap energy and band filling, the absorption band-edge energy increases from 2.58 eV in CdO up to 2.89 eV for 15% Zn, yielding a largely enhanced transparency in the visible. The low required growth temperatures, together with the scalability of CVD deposition, provide an excellent ground for the integration of this TCO ternary alloy on foreign devices.
关键词： Hall effect,ultraviolet-visible absorption,MOCVD,infrared reflectance,CdZnO,Transparent conducting oxides
更新于2025-09-10 09:29:36
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Transparent Heater Based on Al,Ga Co-doped ZnO Thin Films
摘要： Al, Ga co-doped ZnO thin films were deposited on to glass substrates by aerosol assisted chemical transport (AACT) and were studied for application as transparent thin film heaters. The film thickness was around 400 nm after 60 min of AACT deposition; this gave a sheet resistance of 142.5 ?/sq, which corresponded to a resistivity of 5.7 x 10-3 ?.cm. The thin films exhibited a maximum transmittance of 90% in the visible region. A mean temperature of 132.3 oC was reached after applying a voltage of 18 V for 10 min, giving a power consumption of 2.11 W. These results could provide a possibility to use Al, Ga co-doped ZnO thin films as transparent heaters to replace the more expensive indium tin oxide.
关键词： Transparent conducting oxides,microwave synthesis,thin film heater
更新于2025-09-09 09:28:46
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Gallium Oxide || Hydrogen in Ga2O3
摘要： Semiconductors with bandgaps larger than the 3.4 eV bandgap of GaN are emerging as a new class of ultrawide-bandgap (UWBG) electronic materials [1–5]. In spite of the promising applications that are possible for UWBG materials, an understanding of their fundamental properties is at an early stage of development. The focus of this chapter is the hydrogen impurity and its interactions with other defects in β-Ga2O3, a transparent conducting oxide with an ultrawide bandgap of 4.9 eV [6–9]. (It is the most thermally stable monoclinic β phase of Ga2O3 to which we refer throughout this chapter.)
关键词： transparent conducting oxides,Hydrogen,defects,ultrawide-bandgap semiconductors,Ga2O3
更新于2025-09-09 09:28:46
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Structural stability and electronic properties of XTO2 (X= Cu, Ag; T=Al, Cr): an ab initio study including X vacancies and Mg doping
摘要： Ab initio density functional theory-based calculations are used to study the structural and electronic properties of CuAlO2, AgAlO2, CuCrO2, and AgCrO2 transparent conducting oxides (TCOs). The hexagonal 2H delafossite polymorph is determined here to be one of the most stable polymorphs, by comparing total energies for different structural phases. The simple antiferromagnetic configuration is chosen to model magnetic effects in CuCrO2 and AgCrO2 due to it having one of the lowest ground state total energies and containing the most semiconductor like behavior of the magnetic configurations considered. Electronic structures of 2H CuAlO2 and AgAlO2 obtained from different approximations for the exchange-correlation functional, GGA (PBE), PBE+U, PBE+mBJ, PBE+mBJ+U, and the Hybrid HSE06 are compared. Supercells are employed to model 6.25% Cu and Ag vacancies, 3.13% O vacancies, and 6.25% Mg doping replacing Al and Cr, from which structural and electronic properties are obtained and used to predict on the effectiveness of these native defects and dopant on increasing the conductivity in all TCOs studied in this work. The obtained partial density of states for the pristine systems supports a model of hole conduction in the a – b plane, perpendicular to the O – X – O dumbbells of the delafossite structure. Additionally, the partial density of states of the defective and doped systems suggest a growth environment deficient in X and saturated in O may increase conductivity in these materials.
关键词： Delafossite,Density functional theory,Transparent conducting oxides,Mg doping,Structural stability,Ab initio,Vacancies,Electronic properties
更新于2025-09-04 15:30:14
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Mg and N co-doped CuCrO <sub/>2</sub> : A record breaking p-type TCO
摘要： We prepare CuCrO2 thin ?lms with magnesium and nitrogen dopants. The solid state reaction method is employed to produce CuCrO2 targets with three different concentrations of Mg (0%, 2.5%, and 5%). The targets are used in an RF sputtering system to prepare thin ?lms in the presence of N2 as the reactive gas. In this manner, Mg and N atoms, respectively, replace Cr and O sites in the CuCrO2 structure and enhance the electrical and optical properties of the host material. This cationic-anionic substitution yields a superior hole transport and results in an increased conductivity of (cid:2)278 S cm(cid:3)1 which is considered as a record for p-type conductivity in transparent conducting oxides. Moreover, the co-doped CuCrO2 demonstrates a bandgap of 3.52 eV and a transmittance of about 69% in the visible region.
关键词： transparent conducting oxides,RF sputtering,solid state reaction,Mg and N co-doped CuCrO2,p-type TCO
更新于2025-09-04 15:30:14
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European Microscopy Congress 2016: Proceedings || Factors limiting the doping efficiency in atomic layer deposited ZnO:Al thin films: a dopant distribution study by transmission electron microscopy and atom probe tomography
摘要： Transparent conducting oxides (TCOs), such as indium tin oxide (ITO), are commonly used as transparent electrodes in a wide variety of devices, such as in displays and solar cells. ZnO has been reported to be a promising alternative TCO for ITO, because of its lower cost. As the conductivity of intrinsic ZnO films is too low for the applications in mind, doping the ZnO film is essential, the most common dopant being Al. Atomic layer deposition (ALD) is an emerging technique for the deposition of doped ZnO thin films, allowing for accurate thickness control and excellent conformality on high aspect ratio topologies. Due to the self-limiting half-reactions and cyclic nature of the ALD process, not only the aforementioned characteristics can be met, but also the amount and distribution of dopants can be controlled by selecting the precursors (i.e. the Zn or Al precursors) for each individual half-cycle. However, thus far, the maximum conductivity that can be obtained in Al-doped ZnO (ZnO:Al) thin films prepared by ALD appears to be limited by the low doping efficiency of Al. To better understand the origin of this limitation, the 3-dimensional distribution of Al atoms in ZnO films has been examined using a combination of Transmission Electron Microscopy (TEM) and Atom Probe Tomography (APT). For this study, three ZnO:Al films with different Al:Zn ratios were grown sequentially in one film stack, and capped and separated by intrinsic ZnO films. A diagram of the stack is shown in Fig. 1a. This geometry allowed a single APT or TEM measurement to collect data on all three doped films, keeping the analytical conditions identical. BFTEM studies (Fig 1b) showed that for high Al concentrations the ZnO grains are interrupted, while they continue across the lower doped layers. Scanning TEM – High Angle Annular Dark Field (HAADF) imaging and 2-D EDX mappings allows for revealing the aluminum distribution as a function of film depth, showing that the Al-doped layers follow the surface topography of the ZnO grains during growth Fig. 1c,d. However, TEM is limited in providing 3-D dopant distributions, on the one hand because of the limited sensitivity of EDX, on the other hand because of the projection of rough interfaces in a 2-D image. The latter is illustrated in Fig. 2a: individual Al-doped layers can clearly be discerned for larger interspacings, but are poorly recognizable in layer ‘AZO-3’. One-dimensional depth profiles extracted from cylindrical sub-volumes of the 3D APT data (Fig. 2 b) are presented in Fig. 2c. These 1D profiles show that the peaks in Al concentration are no δ-functions, as might be expected from the binary nature of the ALD process. Instead, the peaks have a full width at half maximum (FWHM) of ~2 nm. The 3-dimensional dopant distribution can be used to explain the dependencies of resistivity and doping efficiency on growth recipes used. When the local Al density is too high, the doping efficiency is limited by two proposed limiting factors: the solid solubility limit of Al atoms in a ZnO matrix and the disorder-induced carrier localization.
关键词： atom probe tomography,atomic layer deposition,transparent conducting oxides
更新于2025-09-04 15:30:14