Synergistic effect of Indium and Gallium co-doping on growth behavior and physical properties of hydrothermally grown ZnO nanorods

We synthesized ZnO nanorods (NRs) using simple hydrothermal method, with the simultaneous incorporation of gallium (Ga) and indium (In), in addition, investigated the co-doping effect on the morphology, microstructure, electronic structure, and electrical/optical properties. The growth behavior of the doped NRs was affected by the nuclei density and polarity of the (001) plane. The c-axis parameter of the co-doped NRs was similar to that of undoped NRs due to the compensated lattice distortion caused by the presence of dopants that are both larger (In3+) and smaller (Ga3+) than the host Zn2+ cations. Red shifts in the ultraviolet emission peaks were observed in all doped NRs, owing to the combined effects of NR size, band gap renormalization, and the presence of stacking faults created by the dopant-induced lattice distortions. In addition, the NR/p-GaN diodes using co-doped NRs exhibited superior electrical conductivity compared to the other specimens due to the increase in the charge carrier density of NRs and the relatively large effective contact area of (001) planes. The simultaneous doping of In and Ga is therefore anticipated to provide a broader range of optical, physical, and electrical properties of ZnO NRs for a variety of opto-electronic applications

The resonant interaction between anions or vacancies in ZnON semiconductors and their effects on thin film device properties

Zinc oxynitride (ZnON) semiconductors are suitable for high performance thin-film transistors (TFTs) with excellent device stability under negative bias illumination stress (NBIS). The present work provides a first approach on the optimization of electrical performance and stability of the TFTs via studying the resonant interaction between anions or vacancies in ZnON. It is found that the incorporation of nitrogen increases the concentration of nitrogen vacancies (VN +s), which generate larger concentrations of free electrons with increased mobility. However, a critical amount of nitrogen exists, above which electrically inactive divacancy (VN-VN)0 forms, thus reducing the number of carriers and their mobility. The presence of nitrogen anions also reduces the relative content of oxygen anions, therefore diminishing the probability of forming O-O dimers (peroxides). The latter is well known to accelerate device degradation under NBIS. Calculations indicate that a balance between device performance and NBIS stability may be achieved by optimizing the nitrogen to oxygen anion ratio. Experimental results confirm that the degradation of the TFTs with respect to NBIS becomes less severe as the nitrogen content in the film increases, while the device performance reaches an intermediate peak, with field effect mobility exceeding 50 cm2/Vs. © 2017 The Author(s)2

A Study on the Transition of Copper Oxide by the Incorporation of Nitrogen

In the present study, the effects of nitrogen incorporation on the transition of a p-type copper oxide semiconductor are investigated. The properties of sputtered copper oxide and nitrogen-incorporated copper oxide are evaluated and compared at various nitrogen gas flow rates. The results indicate that the addition of nitrogen results in an increased optical bandgap, accompanied by significantly reduced tail states compared to pristine copper oxide. In addition, X-ray diffraction and X-ray photoelectron spectroscopy reveal that the incorporation of nitrogen stimulates the transition from copper (II) oxide to copper (I) oxide

A Study on the Electrical Properties of Atomic Layer Deposition Grown InO_<i>x</i> on Flexible Substrates with Respect to N₂O Plasma Treatment and the Associated Thin-Film Transistor Behavior under Repetitive Mechanical Stress

Indium oxide (InO_<i>x</i>) films were deposited at low processing temperature (150 °C) by atomic layer deposition (ALD) using [1,1,1-trimethyl-<i>N</i>-(trimethylsilyl)­silanaminato]­indium (InCA-1) as the metal precursor and hydrogen peroxide (H₂O₂) as the oxidant. As-deposited InO_<i>x</i> exhibits a metallic conductor-like behavior owing to a relatively high free-carrier concentration. In order to control the electron density in InO_<i>x</i> layers, N₂O plasma treatment was carried out on the film surface. The exposure time to N₂O plasma was varied (600–2400 s) to evaluate its effect on the electrical properties of InO_<i>x</i>. In this regard, thin-film transistors (TFTs) utilizing this material as the active layer were fabricated on polyimide substrates, and transfer curves were measured. As the plasma treatment time increases, the TFTs exhibit a transition from metal-like conductor to a high-performance switching device. This clearly demonstrates that the N₂O plasma has an effect of diminishing the carrier concentration in InO_<i>x</i>. The combination of low-temperature ALD and N₂O plasma process offers the possibility to achieve high-performance devices on polymer substrates. The electrical properties of InO_<i>x</i> TFTs were further examined with respect to various radii of curvature and repetitive bending of the substrate. Not only does prolonged cyclic mechanical stress affect the device properties, but the bending direction is also found to be influential. Understanding such behavior of flexible InO_<i>x</i> TFTs is anticipated to provide effective ways to design and achieve reliable electronic applications with various form factors

Facile Route to the Controlled Synthesis of Tetragonal and Orthorhombic SnO₂ Films by Mist Chemical Vapor Deposition

Two types of tin dioxide (SnO₂) films were grown by mist chemical vapor deposition (Mist-CVD), and their electrical properties were studied. A tetragonal phase is obtained when methanol is used as the solvent, while an orthorhombic structure is formed with acetone. The two phases of SnO₂ exhibit different electrical properties. Tetragonal SnO₂ behaves as a semiconductor, and thin-film transistors (TFTs) incorporating this material as the active layer exhibit n-type characteristics with typical field-effect mobility (μ_FE) values of approximately 3–4 cm²/(V s). On the other hand, orthorhombic SnO₂ is found to behave as a metal-like transparent conductive oxide. Density functional theory calculations reveal that orthorhombic SnO₂ is more stable under oxygen-rich conditions, which correlates well with the experimentally observed solvent effects. The present study paves the way for the controlled synthesis of functional materials by atmospheric pressure growth techniques

Low temperature activation of amorphous In-Ga-Zn-O semiconductors using microwave and e-beam radiation, and the associated thin film transistor properties

In-Ga-Zn-O (IGZO) films deposited by sputtering process generally require thermal annealing above 300°C to achieve satisfactory semiconductor properties. In this work, microwave and e-beam radiation are adopted at room temperature as alternative activation methods. Thin film transistors (TFTs) based on IGZO semiconductors that have been subjected to microwave and e-beam processes exhibit electrical properties similar to those of thermally annealed devices. However spectroscopic ellipsometry analyses indicate that e-beam radiation may have caused structural damage in IGZO, thus compromising the device stability under bias stress

High-Performance Zinc Tin Oxide Semiconductor Grown by Atmospheric-Pressure Mist-CVD and the Associated Thin-Film Transistor Properties

Zinc tin oxide (Zn–Sn–O, or ZTO) semiconductor layers were synthesized based on solution processes, of which one type involves the conventional spin coating method and the other is grown by mist chemical vapor deposition (mist-CVD). Liquid precursor solutions are used in each case, with tin chloride and zinc chloride (1:1) as solutes in solvent mixtures of acetone and deionized water. Mist-CVD ZTO films are mostly polycrystalline, while those synthesized by spin-coating are amorphous. Thin-film transistors based on mist-CVD ZTO active layers exhibit excellent electron transport properties with a saturation mobility of 14.6 cm²/(V s), which is superior to that of their spin-coated counterparts (6.88 cm²/(V s)). X-ray photoelectron spectroscopy (XPS) analyses suggest that the mist-CVD ZTO films contain relatively small amounts of oxygen vacancies and, hence, lower free-carrier concentrations. The enhanced electron mobility of mist-CVD ZTO is therefore anticipated to be associated with the electronic band structure, which is examined by X-ray absorption near-edge structure (XANES) analyses, rather than the density of electron carriers