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In this study, nc-ZnO films deposited in a Pulsed Laser Deposition (PLD) system at various temperatures were used to fabricate high performance transistors. As determined by Transmission Electron Microscope (TEM) images, nc-ZnO films deposited at a temperature range of 25°C to 400°C were made of closely packed nanocolums showing strong orientation. The influences of film growth temperature and post growth annealing on device performance were investigated. Various gate dielectric materials, including SiO₂, Al₂O₃, and HfO₂ were shown to be suitable for high performance device applications. Bottom-gate FETs fabricated on high resistivity (>2000 ohm-cm) Si substrates demonstrated record DC and high speed performance of any thin film transistors. Drain current on/off ratios better than 10¹² and sub-threshold voltage swing values of less than 100mV/decade could be obtained. Devices with 2μm gate lengths produced exceptionally high current densities of >750mA/mm. Shorter gate length devices (LG=1.2μm) had current and power gain cut-off frequencies, f_T and f_max, of 2.9GHz and 10GHz, respectively.

In this paper a comparative in-situ ellipsometric analysis is carried out on plasma-assisted ALD-grown III-nitride (AlN, GaN, and InN) films. The precursors used are TMA, TMG, and TMI for AlN, GaN, and InN respectively, while Ar is used as purge gas. For all of the films N₂/H₂/Ar plasma was used as the co-reactant. The work includes real-time in-situ monitored saturation curves, unit ALD cycle analysis, and >500 cycle film growth runs. In addition, the films are grown at different substrate temperatures to observe the impact of temperature not only on the growth rate but on how it influenced the precursor chemisorption, ligand removal, and nitrogen incorporation surface reactions. All three nitride films confirm fairly linear growth character. The growth rate per cycle (GPC) for each film is also measured with respect to rf-plasma power to obtain the surface saturation conditions during ALD growth. The real-time in-situ monitoring of the film growth can really be beneficial to understand the atomic layer growth and film formation in each individual ALD cycle.

The attractive key-enabling nanotechnology manufacturing technique of atomic layer deposition (ALD) is well-known to deposit ultra-thin, uniform, conformal and pinhole-free nano-films on complex topography. Over the years it has been used to deposit ultra-thin films in a multitude of industry applications such as microelectronics, solar cells, superconductors, fuel cells, and water purification membranes, among other applications. This study investigates the ALD process effects in the fabrication of Al₂O₃ thin film over the substrate. The mass fraction coverage over the substrate and deposition rate contours in a Gemstar 6 ALD reactor are examined. The analysis technique illustrates the parameter behavior over a Cartesian coordinate sector in a three-dimensional illustration. The governing laws of the conservation of mass, momentum, energy, species, and kinetic chemical reactions are analyzed numerically by ANSYS Fluent and ChemkinPro. The deposition rate profiles correlated with previous experimental findings in the literature, producing an average growth rate of 1.3 Å/cycles.

Al₂O₃ insulator layer was deposited by atomic layer deposition (ALD) technique on p-type Si $〈111〉$ and the Al/Al₂O₃/p-Si metal/insulator/semiconductor (MIS) structures were fabricated. The current–voltage ($I-V$) characteristics of these structures were investigated in two different temperatures. The main electrical parameters such as the ideality factor ($n$), zero bias barrier height (${\mathrm{\Phi }}_{Bo(I-V)}$), and series resistance ($R_s$) values were found for 300 and 400K. The energy density distribution profiles of the interface state density ($N_{ss}$) were determined from the $I-V$ characteristics. In addition, the capacitance–voltage ($C-V$) and conductance–voltage ($G/w-V$) characteristics of devices were investigated in the frequency range 50–1000kHz at room temperature. Frequency-dependent electrical characteristics such as doping acceptor concentration ($N_A$), energy difference between the valance band edge and bulk Fermi level ($E_F$), diffusion potential ($V_{\text{D}}$), barrier height (${\mathrm{\Phi }}_{B(C-V)}$), the image force barrier lowering ($\mathrm{\Delta }{\mathrm{\Phi }}_B$), maximum electric field ($E_m$), and $R_s$ values were determined using $C-V$ and $G/w-V$ plots. In addition, the $N_{ss}$ values were performed using Hill–Coleman method. According to experimental results, the locations of $N_{ss}$ and $R_s$ have an important effect on $I-V$, $C-V$ and $G/w-V$ plots of MIS structure.

We report an investigation of luminescent and tunable photonic crystal structures formed by the infiltration and inversion of opal templates with high index and luminescent materials. Protocols are reported for the deposition of these materials and the properties of the resulting structures investigated by conventional structural and optical measurements. The properties of multi-layered and backfilled structures are reported and demonstrate the potential to modulate and statically tune the luminescence from photonic crystals.

We report the application of atomic layer deposition to manipulate the dielectric architecture of conventional and superlattice two-dimensional photonic crystal waveguides fabricated in silicon. Conformal deposition of a second dielectric layer is shown to have a dramatic influence on the photonic band structure and produces unique effects that cannot be emulated in a single dielectric slab photonic crystal material. With additional dielectric coatings, a strong decrease in photonic band frequencies and change in band slope are observed, which for the lowest photonic states produces strong degeneracies. The capability, in principle, to tune the position of bands to within 0.005% accuracy, is demonstrated. Additionally, new features are observed when differential band shifts result in band-crossing and for which like polarizations activate perturbation mechanisms that result in local and strong band curvatures. The extremely strong band bending resulting from band-band interactions could have applications, in slow light devices, and provide a way to introduce non-linear effects into tunable photonic crystal structures.

Structural color in Nature has been observed in plants, insects and birds, and has led to a strong interest in these phenomena and a desire to understand the mechanisms responsible. Of particular interest are the optical properties of butterflies. In this paper, we review three investigations inspired by the unique optical properties exhibited in a variety of butterfly wings. In the first investigation, conformal atomic layer depositions (ALDs) were used to exploit biologically defined 2D photonic crystal (PC) templates of Papilio blumei with the purpose of increasing the understanding of the optical effects of naturally formed dielectric architectures, and of exploring any novel optical effects. In the second study, it was demonstrated that faithful mimicry of Papilio palinurus can be achieved by physical fabrication methods through using breath figures to provide templates and ALD routines to enable optical properties. Finally, knowledge of the optical structure properties of the Princeps nireus butterfly has resulted in bioinspired designs to enhanced scintillator designs for radiation detection.

In order to improve the interconnection of TiO₂ photoelectrode for the flexible dye-sensitized solar cells (DSSCs) with plastic substrates, thin TiO₂ layers are additionally introduced to the surface of main TiO₂ nanoparticles by atomic layer deposition (ALD) at low temperature. The ALD-induced TiO₂ thin layers on porous films effectively reduced the internal electrical resistance, leading to the facilitated electron transport in DSSCs. As a result, DSSCs with ALD-induced TiO₂ thin layers (thickness of ~ 1.5 nm) showed better power conversion efficiency of 3.09%, which is 33% enhancement compared with that without ALD-induced TiO₂ thin layers (2.32%).

Electron microscopy investigation has been carried for an n-ZnO/p-GaN:Mg heterojunction ultraviolet (UV) light-emitting diode device, where the n-ZnO layer was grown by atomic layer deposition on the p-type GaN:Mg/undoped GaN structure prepared on c-Al₂O₃ substrate. Threading dislocations, formed at the interface of the GaN/Al₂O₃, disappeared at the interface of n-ZnO/p-GaN during post-deposited rapid thermal annealing and accordingly the n-ZnO layer became an almost perfect single crystal including only a few surviving dislocations. An interfacial layer was found along the (0001) interface between the n-ZnO and p-GaN:Mg layers. Scanning transmission microscopy analysis revealed that the interfacial layer was composed of ZnO crystal, which connected coherently with the neighboring n-ZnO and p-GaN:Mg. This interfacial layer contained a few atomic percents of Mg, the atoms of which had been diffused from the p-GaN:Mg. The high quality crystalline n-ZnO and the interfacial layer forming a ZnO/GaN interface states are responsible for the UV electroluminescence from the ZnO.

Surface coating of LiNi${}_{0.5}$Mn${}_{0.3}$Co${}_{0.2}$O₂ (NMC532) is an effective approach to improve the capacity retention and energy density through increasing cutoff operation voltage. In this work, NMC532 electrodes are directly coated with Ta₂O₅ via atomic layer deposition (ALD). The 5 cycles ALD-Ta₂O₅-coated electrodes have the significantly enhanced capacity cyclability. The high-quality amorphous ALD-Ta₂O₅ layer retards the interfacial reaction between NMC532 and electrolyte, and prevents the dissolution of the active materials, improving the phase stability of the NMC532 materials.

Atomic layer deposition (ALD) has long been developed for conformal coating thin films on planar surfaces and complex structured substrates based on its unique sequential process and self-limiting surface chemistry. In general, the coated thin films can be dielectrics, semiconductors, conductors, metals, etc., while the targeted surface can vary from those of particles, wires, to deep pores, through holes, and so on. The ALD coating technique, itself, was developed from gas-phase chemical vapor deposition, but now it has been extended even to liquid phase coating/growth. Because the thickness of ALD growth is controlled in atomic level ($\sim$0.1nm), it has recently been employed for producing two-dimensional (2D) materials, typically semiconducting nanosheets of transition metal dichalcogenides (TMDCs). In this paper, we briefly introduce recent progress in ALD of multifunctional oxides and 2D TMDCs with the focus being placed on suitable ALD precursors and their ALD processes (for both binary compounds and ternary alloys), highlighting the remaining challenges and promising potentials.

In this paper a comparative in-situ ellipsometric analysis is carried out on plasma-assisted ALD-grown III-nitride (AlN, GaN, and InN) films. The precursors used are TMA, TMG, and TMI for AlN, GaN, and InN respectively, while Ar is used as purge gas. For all of the films N₂/H₂/Ar plasma was used as the co-reactant. The work includes real-time in-situ monitored saturation curves, unit ALD cycle analysis, and >500 cycle film growth runs. In addition, the films are grown at different substrate temperatures to observe the impact of temperature not only on the growth rate but on how it influenced the precursor chemisorption, ligand removal, and nitrogen incorporation surface reactions. All three nitride films confirm fairly linear growth character. The growth rate per cycle (GPC) for each film is also measured with respect to rf-plasma power to obtain the surface saturation conditions during ALD growth. The real-time in-situ monitoring of the film growth can really be beneficial to understand the atomic layer growth and film formation in each individual ALD cycle.

In this study, nc-ZnO films deposited in a Pulsed Laser Deposition (PLD) system at various temperatures were used to fabricate high performance transistors. As determined by Transmission Electron Microscope (TEM) images, nc-ZnO films deposited at a temperature range of 25°C to 400°C were made of closely packed nanocolums showing strong orientation. The influences of film growth temperature and post growth annealing on device performance were investigated. Various gate dielectric materials, including SiO₂, Al₂O₃, and HfO₂ were shown to be suitable for high performance device applications. Bottom-gate FETs fabricated on high resistivity (>2000 ohm-cm) Si substrates demonstrated record DC and high speed performance of any thin film transistors. Drain current on/off ratios better than 10¹² and sub-threshold voltage swing values of less than 100mV/decade could be obtained. Devices with 2μm gate lengths produced exceptionally high current densities of >750mA/mm. Shorter gate length devices (L_G=1.2μm) had current and power gain cut-off frequencies, f_T and f_max, of 2.9GHz and 10GHz, respectively.

Si/TiO₂ core/shell nanowires arrays were fabricated using atomic layer deposition of TiO₂ shell on Si nanowires (SiNWs) arrays prepared by metal assisted electroless etching method. After deposition, the Si/TiO₂ nanowires arrays were annealed with different temperature. SEM image shows that annealing makes nanowires gathering on the sample surface. XRD curves indicate that annealing improved the crystalline quality and formed the TiO₂ with anatase phase. Compare to the substrate diffraction peak intensity, annealed at 500°C has strongest diffraction peak intensity. It is demonstrated that TiO₂ shell annealed at 500°C has the best crystalline quality.

Self-assembled monolayers (SAMs) templates of octadecyltrichlorosilane (ODTS) have been prepared controllably. Electrochemical impedance spectroscopy (EIS) has been performed to investigate the size distribution and average distance between the pinhole sites in the ODTS SAMs templates. The result shows that both the size distribution and average distance between the pinhole sites will decrease with the increase of SAMs immersing time. The SAMs templates have been employed to tune the nucleation and growth of Pd nanoparticles (NPs) by atomic layer deposition (ALD). Scanning electron microscope (SEM) images show that the size distribution and particle density of Pd NPs follow the same tendency of the pinhole sites on the templates. Our study reveals that the density of NPs grown on SAMs modified substrates depends on the density of pinholes. With SAMs modified substrate, nanoparticles with uniform size and controlled loading density can be achieved via ALD method.