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The often overlooked and annoying aspects of the propensity of no-oxygen semiconductor kesterite, Cu2ZnSnS4, to oxidation during manipulation and storage in ambient air prompted the study on the prolonged exposure of kesterite nanopowders to air. Three precursor systems were used to make a large pool of the cubic and tetragonal polytypes of kesterite via a convenient mechanochemical synthesis route. The systems included the starting mixtures of (i) constituent elements (2Cu + Zn + Sn + 4S), (ii) selected metal sulfides and sulfur (Cu2S + ZnS + SnS + S), and (iii) in situ made copper alloys (from the high-energy ball milling of the metals 2Cu + Zn + Sn) and sulfur. All raw products were shown to be cubic kesterite nanopowders with defunct semiconductor properties. These nanopowders were converted to the tetragonal kesterite semiconductor by annealing at 500 °C under argon. All materials were exposed to the ambient air for 1, 3, and 6 months and were suitably analyzed after each of the stages. The characterization methods included powder XRD, FT-IR/UV-Vis/Raman/NMR spectroscopies, SEM, the determination of BET/BJH specific surface area and helium density (dHe), and direct oxygen and hydrogen-content analyses. The results confirmed the progressive, relatively fast, and pronounced oxidation of all kesterite nanopowders towards, mainly, hydrated copper(II) and zinc(II) sulfates, and tin(IV) oxide. The time-related oxidation changes were reflected in the lowering of the energy band gap Eg of the remaining tetragonal kesterite component. [ABSTRACT FROM AUTHOR]

The microwave annealing of semiconductor devices has not been extensively researched and is rarely utilized in industry, yet it has the potential to significantly reduce the time and cost associated with large-volume semiconductor processing, such as the various heating and annealing processes required in the manufacture of photovoltaic modules. In this paper, we describe microwave annealing of silicon solar cells, the effective passivation of light-induced defects, and a reduction in light-induced degradation. We find that silicon solar cells are heated rapidly in a microwave field and that effective B–O defect passivation can be achieved by microwave processing in less than 2 s. Microwave annealing yields similar results as compared to rapid thermal annealing. [ABSTRACT FROM AUTHOR]

Precise control of dopant placement is crucial for the reproducible, and reliable, nanoscale semiconductor device fabrication. In this paper, we demonstrate an atomic force microscopy (AFM) probe assisted localized doping of aluminum into an n-type silicon (100) wafer to generate nanoscale counter-doped junctions within two nanometers of the silicon-air interface. The local doping results in changes in electrostatic potential, which are reported as contact potential difference, with nanoscale spatial resolution. In contrast to the literature where nano-mechanical defects in, or contaminants on, silicon substrates can result in measurable changes in the chemical potential of the near-surface, additional thermal treatment was needed to electrically activate the aluminum dopants in our current work. Unfortunately, the thermal activation step also caused the dopants to diffuse and geometric distortions in the doped area, i.e., broadening and blurring of the electrically distinct areas. The results from optimization efforts show that the "active" dopant concentration depended primarily on the thermal anneal temperature; additional AFM-tip dwell time during the aluminum implantation step had no meaningful impact on the electrical activity of the doped sites. [ABSTRACT FROM AUTHOR]

Graphene grown using cold-wall chemical vapor deposition on Cu surfaces follows a classical nucleation and growth mechanism. Following nucleation at the earliest growth stages, isolated crystallites grow, impinge, and coalesce to form a continuous layer. During the pre-coalescence growth regime, the size distributions of graphene crystallites exhibit scaling of the form N(s) = θ/⟨s⟩2g(s/⟨s⟩), where s is the island area, θ is the graphene coverage, ⟨s⟩ is the average island area, N is the areal density, and g(x) is a scaling function. For graphene grown on Cu surfaces that have been annealed in a reducing Ar + H2 ambient, excellent data collapse onto a universal Avrami scaling function is observed irrespective of graphene coverage, surface roughness, or Cu grain size. This result is interpreted to indicate attachment-limited growth and desorption of diffusing C-containing species. Graphene grown on Cu surfaces that were annealed in a non-reducing environment exhibits a qualitatively different scaling function, indicating diffusion-limited growth with a lower attachment barrier combined with C detachment from the graphene edges. [ABSTRACT FROM AUTHOR]

We study the reliability of Al2O3/InGaAs metal-oxide-semiconductor gate stacks by investigating the effect of bias temperature stress on the charge trap density at the Al2O3/InGaAs interface and in the bulk oxide. Under extended negative biasing at 100 °C, the gate stacks display a notable increase in the interface trap density (Dit), but little change in the border trap density. This phenomenon is more prominent for samples exposed to a H2/N2 forming gas anneal (FGA) than for the as-deposited samples. Negative gate bias applied during 100 °C thermal stress negates the FGA-induced passivation of interface states and causes convergence of the Dit of the post-FGA and as-deposited gate stacks with increasing biasing time. This appears to be caused by hydrogen depassivation of interface traps under bias temperature stress, which is further supported by an observed hydrogen isotope effect when comparing the rate of Dit increase after annealing in hydrogenated versus deuterated forming gas. A N2 anneal control experiment also indicates that the stability of the interface trap density of post-FGA Al2O3/InGaAs gate stacks is more strongly influenced by the behavior of hydrogen at the interface than by the thermal treatment effect of the anneal. [ABSTRACT FROM AUTHOR]

Laser melt annealing of amorphous silicon (a-Si) and subsequent recrystallization of a-Si are essential processes for successfully implementing vertical NAND (V-NAND) flash memory devices developed based on the cell-over-periphery (COP) structure. The aim of this study was to develop the numerical model for the laser melting process of a-Si used in V-NAND COP structure. In this study, the numerical simulation predicting the temperature distribution induced by multipath laser scanning and beam overlapping was conducted. In particular, the temperature uniformity and melt duration issues, which are critical in practical laser melt annealing applications in semiconductor fabrication, were discussed based on the simulated temperature distribution results. According to the simulation results, it was found that the annealed surface was subjected to rapid heating and cooling. The heating and cooling rates after temperature stabilization were 4.7 × 107 K/s and 2.04 × 107 K/s, respectively. The surface temperature increased with time and beam overlap ratio owing to the preheating effect and increasing heat accumulation per unit area. Under the process conditions used in the simulation, the temperature in a-Si was far above its melting point (1440 K), which numerically indicated full melting of the a-Si layer. Temperature uniformity within the annealed area was significantly improved when an overlap ratio of 50% was used. It was also found that using an overlap ratio of 50% increased the melt duration by 29.8% compared with an overlap ratio of 25%. [ABSTRACT FROM AUTHOR]

This study employs a three-dimensional numerical model to simulate a vertical furnace for wafer annealing process. For a conventional furnace design, it is revealed that the top 5 pieces of the stacked wafers are exposed to lower temperatures, approximately 3–5 % lower than the operating heater temperature. Temperature distribution and the heat losses from the furnace, especially on the heat dissipated through the top header and the process door of the furnace chamber, are examined. To reduce the heat losses, furnace design improvements comprised of a thicker top header and a better thermal insulated process door are recommended. With such implementations, up to 28 % and 22 % reduction of heat dissipation through the top header and the process door, respectively, could be attained. In addition, the design of the boat cover is found to influence the temperature uniformity across the stacked wafers. To attain better temperature uniformity at the top region of stacked wafers, a furnace with a full boat cover is thus recommended. [ABSTRACT FROM AUTHOR]

We fabricated homogeneous double-layer amorphous Si-doped indium oxide (ISO) thin-film transistors (TFTs) with an insulating ISO cap layer on top of a semiconducting ISO bottom channel layer. The homogeneously stacked ISO TFT exhibited high mobility (19.6 cm²/V s) and normallyoff characteristics after annealing in air. It exhibited normally-off characteristics because the ISO insulator suppressed oxygen desorption, which suppressed the formation of oxygen vacancies (VO) in the semiconducting ISO. Furthermore, we investigated the recovery of the double-layer ISO TFT, after a large negative shift in turn-on voltage caused by hydrogen annealing, by treating it with annealing in ozone. The recovery in turn-on voltage indicates that the dense VO in the semiconducting ISO can be partially filled through the insulator ISO. Controlling molecule penetration in the homogeneous double layer is useful for adjusting the properties of TFTs in advanced oxide electronics. [ABSTRACT FROM AUTHOR]

Reported growth processes for kesterite absorber layers generally rely on a sequential process including a final high temperature annealing step. However, the impact and details for this annealing process vary among literature reports and little is known on its impact on electrical properties of the absorber. We used kesterite absorber layers prepared by a high temperature coevaporation process to explicitly study the impact of two different annealing processes. From electrical characterization it is found that the annealing process incorporates a detrimental deep defect distribution. On the other hand, the doping density could be reduced leading to a better collection and a higher short circuit current density. The activation energy of the doping acceptor was studied with admittance spectroscopy and showed Meyer-Neldel behaviour. This indicates that the entropy significantly contributes to the activation energy. [ABSTRACT FROM AUTHOR]

Silicon dioxide is used to electrically isolate CMOS devices such as fin field effect transistors by filling gaps between the devices (also known as shallow trench isolation). The gap fill oxide typically requires a high temperature anneal in excess of 1000 °C to achieve adequate electrical properties and oxide densification to make the oxide compatible with subsequent fabrication steps such as fin reveal etch. However, the transition from Si-based devices to high mobility channel materials such as SiGe and III-V semiconductors imposes more severe thermal limitations on the processes used for device fabrication, including gap fill oxide annealing. This study provides a framework to quantify and model the effect of anneal temperature and time on the densification of a flowable silicon dioxide as measured by wet etch rate. The experimental wet etch rates allowed the determination of the activation energy and anneal time dependence for oxide densification. Dopant and self-diffusion can degrade the channel material above a critical temperature. We present a model of self-diffusion of Ge and Si in SiGe materials. Together these data allowed us to map the thermal process space for acceptable oxide wet etch rate and self-diffusion. The methodology is also applicable to III-V devices, which require even lower thermal budget. The results highlight the need for nonthermal oxide densification methods such as ultraviolet (UV) and plasma treatments. We demonstrate that several plasma treatments, in place of high temperature annealing, improved the properties of flowable oxide. In addition, UV curing prior to thermal annealing enables acceptable densification with dramatically reduced anneal temperature. [ABSTRACT FROM AUTHOR]

Deep-level defects were investigated by deep level transient spectroscopy on the as-grown and annealed GaNAs layers of various nitrogen (N) contents. The unintentionally doped (uid) GaNAs layers were grown by metalorganic vapor phase epitaxy with N=1.4%, 2.0%, 2.2%, and 2.4% on GaAs substrate. The possible origin and evolution of the deep-level defects upon annealing were analyzed with the use of the GaNAs band gap diagram concept [Kudrawiec et al., Appl. Phys. Lett. 101, 082109 (2012)], which assumes that the activation energy of donor traps decreases with N-related downward shift of the conduction band. On the basis of this diagram and in comparison with previous results, the N-related traps were associated with (N-As)As or (N-N)As split interstitials. It was also proposed that one of the electron traps and the hole trap, lying at the same level position in the bandgap of the annealed uid-GaNAs layers, can both act as one generation-recombination center partially responsible for poor optical properties of this alloy. [ABSTRACT FROM AUTHOR]

In this work, the amorphous Eu3+-doped TiO2 spheres were synthesized by low cost mixed-solvent method, while the anatase and rutile spheres can be obtained by annealing the as-synthesized amorphous TiO2 spheres at elevated temperatures. The optical properties of Eu3+-doped TiO2 spheres were also investigated, and strong red emission (centered at 610 nm) with narrow line-width of 30 nm was observed under 465 nm or 394 nm excitations for the Eu3+-doped anatase TiO2 spheres. Our findings indicate the potential of using Eu3+-doped TiO2 spheres to achieve red emission with InGaN blue light emitting diodes (LEDs). Owing to the high light extraction efficiency in the GaN-based LEDs using anatase TiO2 spheres as demonstrated in our previous works, this work shows the strong potential of Eu3+-doped TiO2 spheres as the red phosphor material for high efficiency GaN-based white light-emitting diode. [ABSTRACT FROM AUTHOR]

The redistribution of hydrogen during solid phase epitaxial regrowth (SPER) of preamorphized silicon has been experimentally investigated, modeled, and simulated for different H concentrations and temperatures. H was introduced by H implantation and/or infiltration from the sample surface during partial thermal anneals in air in the 520-620 °C temperature range. We characterized the time evolution of the H redistribution by secondary ion mass spectrometry and time resolved reflectivity. The good agreement between all experimental data and the simulations by means of full rate equation numerical calculations allows the quantitative assessment of all the phenomena involved: in-diffusion from annealing atmosphere and the H effect on the SPER rate. We describe the temperature dependence of microscopic segregation of H at the amorphous/crystal (a-c) interface. Only a fraction of H atoms pushed by the a-c interface can be incorporated into the crystal bulk. We propose an energetic scheme of H redistribution in amorphous Si. The segregation of H at the a-c interface is also considered for (110) and (111) orientated substrates. Our description can also be applied to other material systems in which redistribution of impurities during a solid-solid phase transition occurs. [ABSTRACT FROM AUTHOR]

In this work, the role of the nitrogen content, the annealing temperature, and the sample morphology on the luminescence properties of Ce3+ and Tb3+ co-doped SiOxNy thin films has been investigated. An increasing nitrogen atomic percentage has been incorporated in the host matrix by gradually replacing oxygen with nitrogen during fabrication while maintaining the Si content unaltered, obtaining a sequential variation in the film composition from nearly stoichiometric SiO2 to SiOxNy. The study of rare earth doped single layers has allowed us to identify the parameters that yield an optimum optical performance from Ce3+ and Tb3+ ions. Ce3+ ions proved to be highly sensitive to the annealing temperature and the nitrogen content, showing strong PL emission for relatively low nitrogen contents (from 0 to 20%) and moderate annealing temperatures (800-1000 °C) or under high temperature annealing (1180 °C). Tb3+ ions, on the other hand, displayed a mild dependence on those film parameters. Rare earth co-doping has also been investigated by comparing the luminescence properties of three different approaches: (i) a Ce3+ and Tb3+ co-doped SiOxNy single layer, (ii) a bilayer composed of two SiOxNy single layers doped with either Ce3+ or Tb3+ ions, and (iii) a multilayer composed of a series of either Tb3+ or Ce3+-doped SiOxNy thin films with interleaved SiO2 spacers. Bright green emission and efficient energy transfer from either Ce3+ ions or Ce silicates to Tb3+ ions has been observed in the co-doped single layer as a consequence of the strong ion-ion interaction. On the other hand, independent luminescence from Ce3+ and Tb3+ ions has been observed in the Ce3+ and Tb3+ co-doped bilayer and multilayer, providing a good scenario to develop light emitting devices with wide color tunability by varying the number of deposited films that contain each rare earth dopant. Moreover, the optoelectronic properties of Ce3+- and/or Tb3+-doped thin films have been studied by depositing transparent conductive electrodes over selected samples. An electroluminescence signal according to the rare earth transitions is obtained in all cases, validating the excitation of Ce3+ and Tb3+ ions upon electron injection. Also, the main charge transport of injected electrons has been evaluated and correlated with the layer stoichiometry. Finally, a simple reliability test has allowed disclosing the origin of the early breakdown of test devices, attributed to the excessive joule heating at filament currents that occur around a region close to the polarization point. [ABSTRACT FROM AUTHOR]

We report on the optimization of structural and electrical properties of SrTiO3 thin films grown on Si (001) by hybrid molecular beam epitaxy. Using a dual buffer layer template, 46-nm-thick films grown at high temperatures (850 °C) resulted in a layer-by-layer growth mode and a good crystalline quality with rocking curve full width at half maximum (FWHM) of the 002 SrTiO3 peak of nearly 0.6°, which was reduced to 0.4° by increasing the film thickness to 120 nm. A high temperature post-deposition anneal was employed to further reduce the rocking curve FWHM down to 0.2° while preserving a smooth film surface morphology. The low sheet resistance of as-grown and post-growth annealed samples was increased by five orders of magnitude exceeding 107 Ω/⇔ using a lower temperature anneal in dry air. This two-step annealing method provides an easy and effective way to improve the crystalline quality of SrTiO3 thin films on Si, providing a path towards the development of electrically insulating, wafer scale virtual perovskite substrates. [ABSTRACT FROM AUTHOR]

FePt and (FePt)91.2Ag8.8 alloy films were deposited by magnetron sputtering. The average coercivity of (FePt)91.2Ag8.8 films reaches 8.51∼105 A/m, which is 0.63∼105 A/m higher than that of the corresponding FePt films. Ag addition effectively promotes the FePt L10 ordering transition at a relatively low annealing temperature of 400 °C. The promotion mechanism was investigated by using in situ high-resolution transmission electron microscopy (HRTEM) and ex situ X-ray absorption fine structure (XAFS). The concurrence of ordering transition and Ag segregation in FePtAg alloy films was first observed by using in situ heating HRTEM. The timeresolved evolution reveals more details on the role of Ag addition in FePt low-temperature ordering. Ex situ XAFS results further confirm that Ag replaces Fe sites in the as-deposited films and segregates from FePt-Ag solid solution phase through annealing at elevated temperatures. The segregation of Ag atoms leaves vacancies in the grain. The vacancy formation is believed to accelerate the diffusion of Fe and Pt atoms, which is critical for the L10 ordering transition. [ABSTRACT FROM AUTHOR]

Effects of high-temperature annealing on deep-level defects in a high-purity semi-insulating 4H silicon carbide substrate have been studied by employing current-voltage, capacitance-voltage, junction spectroscopy, and chemical impurity analysis measurements. Secondary ion mass spectrometry data reveal that the substrate contains boron with concentration in the mid 1015cm-3 range, while other impurities including nitrogen, aluminum, titanium, vanadium and chromium are below their detection limits (typically ~1014cm-3). Schottky barrier diodes fabricated on substrates annealed at 1400-1700 °C exhibit metal/p-type semiconductor behavior with a current rectification of up to 8 orders of magnitude at bias voltages of ±3V. With increasing annealing temperature, the series resistance of the Schottky barrier diodes decreases, and the net acceptor concentration in the substrates increases approaching the chemical boron content. Admittance spectroscopy results unveil the presence of shallow boron acceptors and deep-level defects with levels in lower half of the bandgap. After the 1400 °C annealing, the boron acceptor still remains strongly compensated at room temperature by deep donor-like levels located close to mid-gap. However, the latter decrease in concentration with increasing annealing temperature and after 1700 °C, the boron acceptor is essentially uncompensated. Hence, the deep donors are decisive for the semi-insulating properties of the substrates, and their thermal evolution limits the thermal budget for device processing. The origin of the deep donors is not well-established, but substantial evidence supporting an assignment to carbon vacancies is presented. [ABSTRACT FROM AUTHOR]

The self-assembled formation of ordered, vertically stacked rocksalt/wurtzite MgxZn1-xO heterostructures by planar phase separation is shown. These heterostructures form quasi "natural" two-dimensional hetero-interfaces between the different phases upon annealing of MgO-oversaturated wurtzite MgxZn1-xO layers grown by plasma-assisted molecular beam epitaxy on c-plane sapphire substrates. The optical absorption spectra show a red shift simultaneous with the appearance of a cubic phase upon annealing at temperatures between 900 °C and 1000 °C. Transmission electron microscopy reveals that these effects are caused by phase separation leading to the formation of a vertically ordered rock salt/wurtzite heterostructures. To explain these observations, we suggest a phase separation epitaxy model that considers this process being initiated by the formation of a cubic (Mg,Zn)Al2O4 spinel layer at the interface to the sapphire substrate, acting as a planar seed for the epitaxial precipitation of rock salt MgxZn1xO. The equilibrium fraction x of magnesium in the resulting wurtzite (rock salt) layers is approximately 0.15 (0.85), independent of the MgO content of the as-grown layer and determined by the annealing temperature. This model is confirmed by photoluminescence analysis of the resulting layer systems after different annealing temperatures. In addition, we show that the thermal annealing process results in a significant reduction in the density of edge- and screw-type dislocations, providing the possibility to fabricate high quality templates for quasi-homoepitaxial growth. [ABSTRACT FROM AUTHOR]

Pure α-Al2O3 exhibits a very high degree of thermodynamical stability among all metal oxides and forms an inert oxide scale in a range of structural alloys at high temperatures. We report that amorphous Al2O3 thin films sputter deposited over crystalline Si instead show a surprisingly active interface. On annealing, crystallization begins with nuclei of a phase closely resembling γ-Alumina forming almost randomly in an amorphous matrix, and with increasing frequency near the sub-strate/film interface. This nucleation is marked by the signature appearance of sharp (400) and (440) reflections and the formation of a diffuse diffraction halo with an outer maximal radius of ≈0.23 nm enveloping the direct beam. The microstructure then evolves by a cluster-coalescence growth mechanism suggestive of swift nucleation and sluggish diffusional kinetics, while locally the Al ions redistribute slowly from chemisorbed and tetrahedral sites to higher anion coordinated sites. Chemical state plots constructed from XPS data and simple calculations of the diffraction patterns from hypothetically distorted lattices suggest that the true origins of the diffuse diffraction halo are probably related to a complex change in the electronic structure spurred by the a-γ transformation rather than pure structural disorder. Concurrent to crystallization within the film, a substantially thick interfacial reaction zone also builds up at the film/substrate interface with the excess Al acting as a cationic source. [ABSTRACT FROM AUTHOR]

Cuprous oxide films have been deposited on quartz substrates by a sol-gel method under various annealing temperatures. The X-ray diffraction analysis and Raman scattering show that all the films are of pure Cu2O phase. From comparison of photoluminescence with 488 and 325 nm laser excitations, the electronic transition energies and intensities present the annealing-temperature dependent behavior. The electronic band structures of the Cu2O film annealed at 800 °C, especially for the contribution of exciton series and high energy transitions, have been investigated by temperature dependent transmittance. The extracted refraction index and the high frequency dielectric constant both abruptly decrease until the temperature rises up to 100 K. Six transitions can be clearly identified and the red shift trend of Eo3-Eo5 transition energies with increasing the temperature can be found. Moreover, the anomalous behavior takes place at about 200K from the Eo6 transition. The singularities indicate that the change in the crystalline and electronic band structure occurs as the temperature near 100K and 200K for the film. [ABSTRACT FROM AUTHOR]

The effects of oxygen-plasma treatment on solution-processed Al2Ox gate dielectrics for InGaZnOx (IGZO) thin film transistors (TFTs) are investigated in this paper. Thin films of amorphous Al2Ox are successfully fabricated by annealing temperature of 300 °C. Utilizing oxygen-plasma treated gate dielectrics, combustion-processed IGZO TFTs, which are annealed at a temperature of 300 °C, show a mobility of 7.3 cm²V-1 s-1, a threshold voltage of -0.3 V, an on-off current ratio of 1×105, a subthreshold swing of 160 mV/decade, when operating with a voltage ranging from -2V to +5V. Our experimental results demonstrate that oxygen-plasma treatment can remarkably improve dielectric performance. This is presumably due to the passivation of interfacial and bulk traps, and the reduced concentration of oxygen vacancies. [ABSTRACT FROM AUTHOR]

Rapid thermal annealing is an effective way to improve the optical properties of semiconductor materials and devices. In this paper, the emission characteristics of GaAs0.92Sb0.08/Al0.3Ga0.7As multiple quantum wells, which investigated by temperature-dependent photoluminescence, are adjusted through strain and interfacial diffusion via rapid thermal annealing. The light-hole (LH) exciton emission and the heavy-hole (HH) exciton emission are observed at room temperature. After annealing, the LH and HH emission peaks have blue shift. It can be ascribed to the variation of interfacial strain at low annealing temperature and the interfacial diffusion between barrier layer and well layer at high annealing temperature. This work is of great significance for emission adjustment of strained multiple quantum wells. [ABSTRACT FROM AUTHOR]

Nanocrystalline silicon carbide (nc-SiC) is an interesting material for electronics applications, both in its own right and as a host matrix for silicon quantum dots. When synthesized by annealing of a-SiC:H on Si substrates, interdiffusion of dopants occurs if either the a-SiC:H or the Si substrate is doped. Annealing a-SiC:H on highly boron-doped substrates at 1100 °C leads to a fairly homogeneous doping level of ≥4×1019 cm-3 throughout the nc-SiC film. An unexpected anomaly in secondary ion mass spectroscopy quantification is observed and a method to circumvent it is shown. The nanostructure of the nc-SiC is only weakly affected as most of the diffusion occurs after the onset of crystallization. Annealing of doped a-SiC:H on Si substrates at 1100 °C leads to strong free carrier absorption at infrared wavelengths. This is demonstrated to originate from dopants that have diffused from the a-SiC:H to the Si substrate, and a method is developed to extract from it the doping profile in the Si substrate. The detection limit of this method is estimated to be ≥6×1013 cm-2. Doping levels of (0.5-3.5)×1019 cm-3 are induced at the Si substrate surface by both boron and phosphorus-doped a-SiC:H. When the Si substrate is doped opposite to the a-SiC:H p-n junctions are induced at a depth of 0.9-1.4 lm within the Si substrate for substrate resistivities of 1-10 Ω cm. Implications for different solar cell architectures are discussed. Dopant diffusion can be strongly reduced by lowering the annealing temperature to 1000 °C, albeit at the expense of reduced crystallinity. [ABSTRACT FROM AUTHOR]

The influence of SiO2 and SiNx cover layers on the dopant distribution as well as microstructure of high fluence Ga implanted Si after thermal processing is investigated. The annealing temperature determines the layer microstructure and the cover layers influence the obtained Ga profile. Rapid thermal annealing at temperatures up to 750°C leads to a polycrystalline layer structure containing amorphous Ga-rich precipitates. Already after a short 20?ms flash lamp annealing, a Ga-rich interface layer is observed for implantation through the cover layers. This effect can partly be suppressed by annealing temperatures of at least 900°C. However, in this case, Ga accumulates in larger, cone-like precipitates without disturbing the surrounding Si lattice parameters. Such a Ga-rich crystalline Si phase does not exist in the equilibrium phase diagram according to which the Ga solubility in Si is less than 0.1 at. %. The Ga-rich areas are capped with SiOx grown during annealing which only can be avoided by the usage of SiNx cover layers. [ABSTRACT FROM AUTHOR]

To enable an understanding and optimization of the optoelectronic behavior of CdTe-ZnO nanocomposites, the morphological and chemical properties of annealed CdTe/ZnO interface structures were studied. For that purpose, CdTe layers of varying thickness (4-24 nm) were sputter-deposited on 100 nm-thick ZnO films on surface-oxidized Si(100) substrates. The morphological and chemical effects of annealing at 525 °C were investigated using X-ray Photoelectron Spectroscopy (XPS), X-ray-excited Auger electron spectroscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy, and atomic force microscopy. We find a decrease of the Cd and Te surface concentration after annealing, parallel to an increase in Zn and O signals. While the as-deposited film surfaces show small grains (100 nm diameter) of CdTe on the ZnO surface, annealing induces a significant growth of these grains and separation into islands (with diameters as large as 1 μm). The compositional change at the surface is more pronounced for Cd than for Te, as evidenced using component peak fitting of the Cd and Te 3d XPS peaks. The modified Auger parameters of Cd and Te are also calculated to further elucidate the local chemical environment before and after annealing. Together, these results suggest the formation of tellurium and cadmium oxide species at the CdTe/ZnO interface upon annealing, which can create a barrier for charge carrier transport, and might allow for a deliberate modification of interface properties with suitably chosen thermal treatment parameters. [ABSTRACT FROM AUTHOR]

Superlattices containing 3 nm thick silicon rich silicon nitride sublayers and 3 nm and 10 nm thick SiO2 barriers were prepared by plasma enhanced chemical vapor deposition. Despite the as-prepared samples represented a well-kept multilayer structure with smooth interfaces, the high temperature annealing resulted in the total destruction of multilayer structure in the samples containing 3 nm SiO2 barriers. Energy-filtered transmission electron microscopy images of these samples indicated a silicon nanoclusters formation with sizes of 2.5-12.5 nm, which were randomly distributed within the structure. Although in the sample with 10 nm SiO2 barriers some fragments of the multilayer structure could be still observed after thermal annealing, nevertheless, the formation of large nanocrystals with diameters up to 10 nm was confirmed by dark field transmission electron microscopy. Thus, in contrast to the previously published results, the expected size control of silicon nanocrystals was lost. According to the FTIR results, the thermal annealing of SiNx/SiO2 superlattices led to the formation of silicon nanocrystals in mostly oxynitride matrix. Annealed samples demonstrated a photoluminescence peak at 885 nm related to the luminescence of silicon nanocrystals, as confirmed by time-resolved photoluminescence measurements. The loss of nanocrystals size control is discussed in terms of the migration of oxygen atoms from the SiO2 barriers into the silicon rich silicon nitride sublayers. A thermodynamic mechanism responsible for this process is proposed. According to this mechanism, the driving force for the oxygen migration is the gain in the configuration entropy related to the relative arrangements of oxygen and nitrogen atoms. [ABSTRACT FROM AUTHOR]

The formation of nanoscale protein filaments from soluble precursor molecules through nucleated polymerization is a common form of supra-molecular assembly phenomenon. This process underlies the generation of a range of both functional and pathological structures in nature. Filament breakage has emerged as a key process controlling the kinetics of the growth reaction since it increases the number of filament ends in the system that can act as growth sites. In order to ensure microscopic reversibility, however, the inverse process of fragmentation, end-to-end annealing of filaments, is a necessary component of a consistent description of such systems. Here, we combine Smoluchowski kinetics with nucleated polymerization models to generate a master equation description of protein fibrillization, where filamentous structures can undergo end-to-end association, in addition to elongation, fragmentation, and nucleation processes. We obtain self-consistent closed-form expressions for the growth kinetics and discuss the key physics that emerges from considering filament fusion relative to current fragmentation only models. Furthermore, we study the key time scales that describe relaxation to equilibrium. [ABSTRACT FROM AUTHOR]

The epitaxial La0.7Sr0.3MnO3/BaTiO3 (LSMO/BTO) bilayer ?lms are grown on (001) oriented LaAlO3 substrate by pulsed laser deposition technique. The oxygen-rich interface is obtained through in-situ annealing process in oxygen, and the oxygen-deficient interface is obtained without the annealing process. The results show that the ferromagnetic properties of the LSMO film and the magnetoelectric effect (ME) of the bilayer films strongly correlate to the oxygen content at the interface of LSMO/BTO. The saturated magnetization and the ME voltage coefficient of the oxygen-rich bilayer film are higher than that of oxygen-deficient one. It suggests a more effective ME coupling at the LSMO/BTO interface, which are generated through not only the interface strain but also the spin polarized carriers. [ABSTRACT FROM AUTHOR]

10nm and 50nm Co2FeAl (CFA) thin films have been deposited on MgO(001) and Si(001) substrates by magnetron sputtering and annealed at different temperatures. X-rays diffraction revealed polycrystalline or epitaxial growth (according to CFA(001)[110]//MgO(001)[100] epitaxial relation) for CFA films grown on a Si and on a MgO substrate, respectively. For these later, the chemical order varies from the A2 phase to the B2 phase when increasing the annealing temperature (Ta), while only the A2 disorder type has been observed for CFA grown on Si. Microstrip ferromagnetic resonance (MS-FMR) measurements revealed that the in-plane anisotropy results from the superposition of a uniaxial and a fourfold symmetry term for CFA grown on MgO substrates. This fourfold anisotropy, which disappears completely for samples grown on Si, is in accord with the crystal structure of the samples. The fourfold anisotropy field decreases when increasing Ta, while the uniaxial anisotropy field is nearly unaffected by Ta within the investigated range. The MS-FMR data also allow for concluding that the gyromagnetic factor remains constant and that the exchange stiffness constant increases with Ta. Finally, the FMR linewidth decreases when increasing Ta, due to the enhancement of the chemical order. We derive a very low intrinsic damping parameter (1.1 x 10-3 and 1.3 x 10-3 for films of 50nm thickness annealed at 615 °C grown on MgO and on Si, respectively). [ABSTRACT FROM AUTHOR]

Organic photovoltaics (OPVs) can potentially provide a cost-efficient means of harnessing solar energy. However, optimum OPV performance depends on understanding the process–structure–property (PSP) correlation in organic semiconductors. In the working of bulk-heterojunction OPVs, the morphology plays a crucial role in device performance. In order to understand PSP linkage, a theoretical framework has been developed. We first established process–structure correlations by generating a range of morphologies with various blend ratios of donor and acceptor organic semiconductors for various annealing periods. Second, we calculated the effective electronic properties corresponding to the simulated structures using a diffuse interface approach that is numerically more robust and straightforward than the classical sharp interface method. This novel framework, wherein both the process–structure and the structure–property relationship have been established using the diffuse interface approach, completes the theoretical PSP linkage, allowing the optimization of process parameters for device applications. The theoretical PSP linkage is then benchmarked qualitatively with experimental results on a model P3HT:PCBM system. We have been able to identify the morphological characteristics that maximize device performance. This work is carried out in the broad overview of the integrated computational materials engineering framework wherein the processing parameters are optimized by determining the process–structure–property relationships. [ABSTRACT FROM AUTHOR]

Thin-film transistors (TFTs) fabricated using solution-processed zinc–tin-oxide (ZTO) semiconductor thin films as the channel layers are proposed in this paper. Effect of the ZTO annealing temperature on the TFT performance is studied. Significant reduction of oxygen-vacancy and chlorine residue contents in the ZTO semiconductor can be obtained when the annealing temperatures are 500 °C–700 °C. The ZTO semiconductor with the annealing process at 600 °C in air can give an optimal ZTO TFT having a low leakage current of 10−12 A and a high ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ ratio of 3 $\times \,\,10^{7}$. The subthreshold swing is 0.39 V/decade corresponding to an interface trap density of $1.2\times \,\,10^{12}\,\,$ cm−2eV−1. [ABSTRACT FROM AUTHOR]

In this work, aluminum-doped zinc oxide (AZO) films were annealed under argon flux at different temperatures and cooled down slowly to room temperature. Afterward, optical properties of samples were studied and their optical band gap were estimated by different methods such as dR/dλ (3.33–3.83 eV), dT/dλ (3.8–4.1 eV), optical conductivity (3.7–4.53 eV), dielectric relaxation time (3.65–3.87 eV), d(αhν)/dhν (3.44–3.95 eV), Tauc power law (3.4–4 eV), and the single oscillator model (2.67–3.37 eV). Increasing annealing temperature caused a redshift in the maximum of the dielectric relaxation time (τ) peaks. The dispersion parameters were studied through single oscillator model. The oscillator strength (f) and the dispersion energy (Ed) of films were decreased by increasing annealing temperature so that the films annealed at 600 ∘C had minimum Urbach' s energy (Eu) of 0.05 eV with minimum disordered. Due to high Al content, asdeposited films had maximum dielectric constant at higher wavelength (ε∞) [ABSTRACT FROM AUTHOR]

Abstract Silicon (Si) has been the most widely used semiconductor for decades, playing an important role in the field of electronics, energy conversion and energy storage. Because of their unique morphological energy band characteristics, Si nanostructures exhibit superior performance in many applications in comparison with their bulk counterparts. In this study, the effects of thermal annealing on elemental composition and morphological properties of palladium metal thin films grown on c-Si substrates were investigated. Palladium (Pd) thin films of different thicknesses were deposited on Si (1 0 0) with and without native oxide layers by electron beam evaporation and annealed in vacuum at 600 °C for two hours. Scanning electron microscopy (SEM) studies have shown that the surface morphology showed an effective dewetting in individual droplets and islands which further coalesce into bigger islands. Rutherford backscattering spectrometry (RBS) and electrical measurements analyses revealed the diffusion of the Si substrate into the Pd layer during annealing. This contribution will discuss the effects of the metal layer thickness as well as the native oxide on the metal thin films. [ABSTRACT FROM AUTHOR]

Abstract This work reports on the effect of high temperature annealing on the electrical properties of p-type implanted 4H-SiC. Ion implantations of Aluminum (Al) at different energies (30–200 keV) were carried out to achieve 300 nm thick acceptor box profiles with a concentration of about 1020 at/cm3. The implanted samples were annealed at high temperatures (1675–1825 °C). Morphological analyses of the annealed samples revealed only a slight increase of the surface roughness RMS up to 1775 °C, while this increase becomes more significant at 1825 °C (RMS = 1.2 nm). Room temperature Hall measurements resulted in a hole concentration in the range 0.65–1.34 × 1018/cm3 and mobility values in the order of 21–27 cm2 V−1 s−1. The temperature dependent electrical measurements allowed to estimate an activation energy of the Al-implanted specie of about 110 meV (for the post-implantation annealing at 1675 °C) and a fraction of active p-type Al-dopant ranging between 39% and 56%. The results give useful indications for the fabrication of 4H-SiC JBS and MOSFETs. [ABSTRACT FROM AUTHOR]

Abstract In the present work, the effect of the post-deposition annealing process in an air atmosphere on the structural and magnetic properties of the ternary Fe/SnO 2 /Fe thin film, deposited by the sputtering technique was reported. X-ray diffraction (XRD) pattern confirms the formation of alpha-iron, magnetite and tin dioxide phases in the as-deposited film. Meanwhile, after the thermal annealing, the formation of hematite and tin dioxide phases was determined. Magnetization (M) measurements reveal some features after the annealing: i) a reduction of the coercive field (H C), which has been assigned to the presence of hematite, and ii) the transformation of alpha-iron/magnetite phases into the hematite phase in accordance with results obtained from XRD data analysis. Those results were also confirmed by room temperature Conversion electron Mössbauer spectroscopy (CEMS) measurements carried out using a 57Co(Rh) source. Furthermore, the doublets of the CEMS spectrum of the as-deposited film (21%) has been assigned to the signal of Fe3+ and Fe2.5+ (mixture of Fe3+ and Fe2+) ions, which diffuse into the SnO 2 matrix. The spectral area of those doublets is clearly reduced to 3% after the thermal annealing. It suggests the migration of the Fe ions from the non-magnetic phase to the magnetic phase. On the other hand, CEMS spectrum of the as-deposited film carried out with using a 119 mSn source is well modeled with a doublet and a sextet. The doublet was assigned to Sn4+ ions of the SnO 2 phase; meanwhile, the sextet was assigned to Sn4+ ions located at interstitial and/or substitutional sites of the alpha-iron/magnetite phases. Those tin ions sense the supertransferred hyperfine field from Fe neighbor. After the thermal annealing, the CEMS spectrum was well modeled with only a doublet related to SnO 2 phase, suggesting that the tin ions have been out diffused from the magnetic phase (alpha-iron and magnetite) and incorporate into the no magnetic o-SnO 2. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the influence of thickness and post deposition annealing temperature on thermally evaporated molybdenum oxide films has been studied. The X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) are used for crystal structural and surface morphological characterization of the films, respectively. The XRD analysis showed that the presence of α-MoO 3 and MoO 2 crystalline phase of the films annealed at elevated temperature ~ 250 °C after deposition. The optical constants are determined from UV–Vis transmission spectra. The optical band gap and Urbach energy is found to be temperature dependent. The refractive index of the films is estimated by the optical method as well as cross-sectional SEM image analysis. It is found that the refractive index of the films increases from ~ 1.70 to 2.03 with the decrease in film thickness from ~ 2.9 to 1.7 µm. It is also observed that the refractive index decreased from ~ 2.03 to 1.61 with the increase in post deposition annealing temperature from room temperature (RT) to ~ 250 °C. Moreover, extinction coefficient, optical conductivity, porosity, and film density are investigated as a function of source-substrate distance and post deposition annealing temperature. The Photoluminescence (PL) properties of the films are also investigated by recording spectra under the excitation wavelength at 250 nm. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

It has been reported that Ar plasma treatment on the n-type 4H-SiC surface before metal deposition can reduce the contact resistance. In that work, the n+ layer was formed by ion implantation at room temperature (RT). In this paper, it is found that Ar plasma treatment on the high-temperature (HT) implanted n+ layer degrades but not improves the contact resistance. A composition of RT/low-energy and HT/high-energy ion implantation can achieve low sheet resistance of the n+ layer and low contact resistance simultaneously. A twofold mechanism is proposed that the amorphous interfacial layer produced by Ar plasma treatment reduces the Schottky barrier height and the defects generated by RT ion implantation enhance current conduction by trap-assisted tunneling. [ABSTRACT FROM AUTHOR]

We propose a simple and inexpensive strategy for fabricating aqueous route indium oxide thin-film transistors (In2O3-TFTs) at much lower annealing temperatures (${T}_{\text {a}}= 140\,\,^{\circ }\text{C}$) using NH3 plasma-assisted treatment (PAT) process to In2O3 film surfaces. During the NH3 PAT, the substrate temperature, plasma power, and gas flow were maintained at 140 °C, 50 W, and 100 sccm, respectively. The effect of a sequence of postannealing and PAT, namely, anneal after plasma (AAP)/anneal before plasma (ABP), was studied in detail. The results show that the NH3 PAT can promote the fracture of −OH, passivate the Vo, and increase the conductivity of In2O3 films at low temperatures. The AAP instead of ABP is a suitable method to realize high-performance low-temperature processed In2O3-TFTs on account of the higher oxidation degree, appropriate N doping, as well as more effectively H doping in AAP sample. The fabricated In2O3-TFTs based on AAP exhibited acceptable electrical performance of ~1.3 cm2/ $\text {V}\cdot \text {s}$ mobility and ~107 on/off current ratio at low temperatures. The novel method for fabricating the In2O3-TFTs opens a way for the development of nontoxic, low-cost, and low-temperature oxide circuitry. [ABSTRACT FROM AUTHOR]

Recently, p-type metal–oxide–semiconductors have attracted considerable interests for the applications in optoelectronic devices and low-power complementary metal–oxide–semiconductor circuits. In this report, ternary p-type CuAlxOy semiconductor thin films were fabricated by sol–gel method and integrated as channel layers in thin-film transistors (TFTs). The electrical performances of CuAlxOy TFTs, together with the characteristics of CuAlxOy thin films (e.g., crystalline phases, chemical compositions, surface morphology, and optical transmittances), were systematically studied at various annealing temperatures (${T}_{a}$). The phase-pure CuAlO2 thin films were obtained at ${T}_{a}$ above 800° C in N2 atmosphere. CuAlO2 TFTs annealed at 900 ° C based on high-k Al2O3 exhibited optimized electrical performance, including a hole mobility of 1.36 cm2/Vs and on/off current ratio of $\sim 1 \times 10^{\textsf {5}}$. This paper not only demonstrates the successful fabrication of high-quality p-type CuAlO2 semiconductor thin film and electronic devices by sol–gel process but also provides guidelines for related ternary p-type oxide semiconductor material and device performance improvements. [ABSTRACT FROM AUTHOR]

We report on the demonstration and investigation of Ta2O5 as high-k dielectric for InAlN/GaN-MOS high-electron mobility transistor (HEMT)-on-Si. Ta2O5 of thickness 24 nm and dielectric constant ~30 was sputter deposited on InAlN/GaN HEMT and was investigated for different post deposition anneal (PDA) conditions. The gate leakage was 16 nA/mm at −15 V which was ~five orders of magnitude lower compared to reference HEMT. The 2-D electron gas (2-DEG) density was found to vary with annealing temperature suggesting the presence of net charge at the Ta2O5/InAlN interface. Dispersion in the capacitance–voltage (${C}$ – ${V}$) characteristics was used to estimate the frequency-dependent interface charge, while energy band diagrams under flat band conditions were investigated to estimate fixed charge. The optimum anneal condition was found to be 500 °C which has resulted into a flat band voltage spread ($\Delta {V}_{\text {FB}}$) of 0.4 V and interface fix charge (${Q} _{\text {f}}$) of ${3.98} \times {10}^{{13}}$ cm $^{-2}$. X-ray photoelectron spectroscopy spectra of as-deposited and annealed Ta2O5film were analyzed for Ta and O compositions in the film. The sample annealed at 500 °C has shown Ta:O ratio of 0.41. X-ray diffraction analysis was done to check the crystallization of amorphous Ta2O5 film at higher annealing temperatures. [ABSTRACT FROM AUTHOR]

We report a potential method for the fabrication of Si-based Ge film with low threading dislocation (TD) density (<105 cm−2) based on a low-temperature Ge/Si wafer bonding and smart cut technique. This method may replace the traditional epitaxial growth to solve the problems related to the TDs, high temperature, and high vacuum. A near-bubble-free Ge/Si bonded interface is achieved for the fabrication of Ge/Si p-i-n photodiodes. The insertion of amorphous Ge (a-Ge) has crystallized after Ge layer exfoliation, achieving a small FWHMXRD (96 arcsec) of the Ge peak. This determines the low dark current density (5.97 mA/cm2) and low ideality factor (1.19) of the Ge/Si p-i-n photodiode. The exfoliated Ge film suffers from in-plane compression strain due to the expansion of the H2 gas during the blistering process. Interestingly, the in-plane compression strain turns into tensile strain after high-temperature postannealing due to the faster shrinkage rate of Ge during cooling. The in-plane tensile strain leads to the increase in the responsivity of the photodiode. The responsivity of the photodiode at 1310 nm increases from 0.505 to 0.71 A/W and that at 1550 nm increases from 0.244 to 0.524 A/W after postannealing. More importantly, the redshift of the absorption edge of the Ge/Si photodiode (0.1 A/W at 1630 nm) is also observed. This implies that the wafer-bonded Ge/Si p-i-n photodiode can be comparable with the epitaxial one and can be used for optical communication in all wavelength division multiplexing bands, including the ${L}$ -band (1565–1625 nm) and entire ${C}$ -band (1530–1565 nm). [ABSTRACT FROM AUTHOR]

Abstract This paper presents investigation on the effects of annealing temperature towards surface morphological and optical properties of black silicon (b-Si) fabricated by a two-step silver-assisted chemical etching process. Crystalline (c-Si) wafers are deposited with a thin film silver (Ag) layer. The c-Si wafers are annealed in nitrogen atmosphere for 40 min at different temperatures (200–260 ℃) to form Ag nanoparticles. The wafers are then etched in the aqueous solution of HF:H 2 O 2 :DI H 2 O at room temperature for 70 s. The results show that the surface morphologies of all samples are rough due to the presence of b-Si nanotextures. The b-Si wafers demonstrate significantly lower broadband reflection compared to the planar reference. The b-Si wafer annealed at 230 ℃ demonstrates the lowest reflection (3%) and highest absorption (97%) at the wavelength of 600 nm. This sample exhibits b-Si nanotextures with average width less than 50 nm and height of 245 nm. The enhanced broadband light absorption in the best b-Si wafer gives the highest maximum potential short-circuit current density (J sc(max)) of 39.6 mA/cm2, or enhancement 50.6% compared to the planar c-Si reference wafer, calculated for wavelength region of 300–1100 nm. [ABSTRACT FROM AUTHOR]

Abstract The present paper studies the structural, compositional, morphological and optical properties of thin CdS/CdSe stacks annealed in an inert atmosphere or subjected to a CdCl 2 treatment. The bilayer stacks were fabricated by chemical bath deposition (CBD) of a 50 nm thick CdS layer followed by evaporation of a CdSe film with equal thickness. It was found that when this stack was annealed at 400 °C for up to 10 min, no appreciable intermixing/alloying between the two layers was detected. Upon heating for 5–10 min in presence of a CdCl 2 layer disposed over the CdSe film, however, led to appreciable alloying and formation of CdSSe, which was confirmed through XRD, optical transmission and room temperature photoluminescence measurements. XRD data further showed that the CdS layer in the CdS/CdSe stack had nano-amorphous structure that did not change upon annealing in inert atmosphere. The CdSe layer of the stack, which had a cubic structure, also preserved its phase upon annealing in inert atmosphere. When the CdS/CdSe stack was CdCl 2 treated, the phase of the CdSSe alloy formed was transformed to hexagonal. These observations may have consequences in applications where CdS/CdSe bilayers are formed within device structures and subjected to various types of heat treatments. [ABSTRACT FROM AUTHOR]

Abstract Light emitting diodes (LEDs) based on n-SnO 2 /p-GaN heterojunction were fabricated by pulsed laser deposition (PLD). The effects of post-annealing treatment and interfacial layers on electroluminescence (EL) of n-SnO 2 /p-GaN were investigated. After annealing in vacuum, all the LED devices with different interfacial layers exhibit a nonlinear current-voltage behavior. The SnO 2 /p-GaN light emitting diodes exhibit two emission peaks, a violet peak (410 nm) and the broad yellow-orange emission band (600–700 nm), whereas only the yellow-orange EL spectra could be found in the SnO 2 /AlN/p-GaN. Using the band diagram, the carrier blocking process by different interfacial layer and the electroluminescence mechanisms of heterojunction LEDs were discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract Effective carrier contact with excellent surface passivation is essential for archiving high efficiency silicon solar cells. In this study, optical, passivation and stoichiometric characteristics of MoO x thin films were analyzed by varying thickness, temperature and ambient annealing. The 10 nm thick MoO x films showed high optical transmittance (89.81%) in the visible near infra-red (NIR) wavelength (380–1100) nm region and wide optical bandgap of 3.25 eV. An improved minority carrier lifetime of 2.24 ms was recorded for O 2 ambient at 130 °C due to less additional defects in the MoO x films. X-rays photoelectron spectroscopic analysis confirmed that O 2 ambient annealing greatly influenced the MoO x stoichiometric and reduce the formation defective state densities at the Fermi energy initiating from the tail of an oxygen vacancy and inducted the defect band within the energy bandgap. Carrier selective contact (CSC) solar cells were fabricated by using 10 nm thick MoO x film as hole extraction layer exhibited the high performance as; open circuit voltage (V oc) = 708 mV, current density (J sc) = 37.80 mA/cm2, fill factor (FF) = 74.95% and efficiency (η) = 20.06%. These results implies that the MoO x is an important material to use in future CSC solar cell applications with the concept of new advantages such as dopant free, non-toxic and low temperature fabrication process. [ABSTRACT FROM AUTHOR]

Annealing effects on microstructure and magnetic properties of (NdPr)9.5(FeNbCo)79.5(BC)11 ribbons were investigated. It was observed that Nd2Fe14B and Fe3B phases were directly formed at low spinning speed. Then, the alloys transformed to an amorphous state at a speed of 20 m/s. Annealed at 700 ∘C for 10 min, the amorphous alloys as-quenched at 20 m/s crystallized into a nanocomposite composed of Nd2Fe14B and α -Fe phases. The formation of Fe3B phases was inhibited. The magnetic properties firstly increased and then decreased with the increasing of annealing time. The optimum magnetic properties were achieved in the alloys annealed at 700 ∘C for 10 min. The corresponding coercivity, remanence, and the maximum energy product was 427.5 kA/m, 0.94 T, and 101.2 kJ/m3, respectively. In addition, fine and uniform grains were formed. The average grain size was 10 nm. [ABSTRACT FROM AUTHOR]

A way to stabilize the domain structure in periodically poled Rb-doped KTiOPO4 samples at high-temperatures is presented. The domain contraction along the b-crystallographic axis that is observed when crystals are annealed at high temperatures is suppressed when the ends of the domains along the b-axis are diced away. Additionally, the thermal stability of self-assembled domain gratings with a sub-μm average periodicity of 650 ± 200 nm and a domain-width of 225 ± 75 nm in mm-thick samples is investigated, and it is shown that the key factor for the domain stability is the domain width rather than the interdomain distance. [ABSTRACT FROM AUTHOR]

High efficiency, lightweight, and tunable microwave absorbing materials have drawn tremendous attention. Here, we have synthesized layered GeP5 bulk at high temperature and high pressure. Then, the GeP5 nanosheets are obtained by an efficient liquid-phase exfoliation method and display excellent microwave absorption performance as a microwave absorber. The reflection loss (RL) can achieve below −10 dB in a wide range of thicknesses and microwave frequencies. For further meeting the lightweight demand of microwave absorption materials, porous germanium (GeP5-570) is obtained from GeP5 via the annealing treatment. Microwave absorption characteristics can be significantly improved after annealing treatment. The minimum RL values of porous germanium (GeP5-570) can reach −37.8 dB at a microwave frequency of 4.7 GHz under a thickness of 2.9 mm. The effective absorption bandwidth (RL< −10 dB) of GeP5-570 is 11.8–14.3 GHz with a thickness of 1.2 mm. In addition, the RL value can attain −20 dB in the frequency range of 3.8–16.1 GHz with various thicknesses from 1.0 to 3.5 mm. [ABSTRACT FROM AUTHOR]