Post Thermal Annealing Treatment Research Articles

Open-circuit photopotential characterization of photoelectrochemical activities of Au-modified TiO2 nanorods

The open circuit potential (OCP) of a semiconductor electrode can be used to quantify the transient photopotential (Ep), which represents wavelength-dependent charge accumulation and relaxation kinetics of a photoelectrode. Here OCP responses of a plasmonic Au@TiO2 nanorods (NRs) photoelectrode can be quantified without causing electrochemical corrosion of Au. The photogenerated charge accumulation kinetics data based on the wavelength-dependent growth rates of |Ep| can resolve the plasmonic effects on photoelectrochemistry (PEC) of Au@TiO2 NRs. Data fitting with Kohlrausch-Williams-Watts (KWW) stretched exponential kinetics model illustrates the complex charge relaxations at the Au/TiO2 Schottky contact, from which long relaxation lifetimes with broad lifetime distributions can be obtained. This is attributed to the abundant deep defects in the nanostructure TiO2, which has been strongly confirmed by reducing the oxygen vacancies using a post-thermal annealing treatment. Single-particle dark-field scattering (DFS) spectrum is measured with a tunable wavelength light source to support visible light activities of PEC characteristics of Au@TiO2 NRs. Light scattering spectra of >200 single Au@TiO2 NRs particles are collected to compare directly with PEC responses of OCP of the ensemble Au@TiO2 NRs.

Toward non-gas-permeable hBN film growth on smooth Fe surface

Flexible, transparent, and thermally stable gas barrier films are required to seal organic-based ultra-thin, flexible, and transparent electronic devices against moisture. Thermally stable, two-dimensional hexagonal boron nitride (hBN) is an ideal non-gas-permeable material with high transparency and flexibility. Nevertheless, the polycrystalline multilayer hBN (m-hBN) grown on a rough Fe foil by chemical vapor deposition is not sufficient for use as a gas barrier due to the non-uniformity and discontinuity of the film. Here, we report a novel method for synthesizing highly uniform and continuous m-hBN films on smooth Fe foil on a wafer scale via deposition of an amorphous Fe layer on a rough Fe foil. The amorphous Fe layer on a unary Fe foil is effectively recrystallized to become a smooth surface via post-thermal annealing treatment at 1100 °C. The smoothed surface allows for the uniform precipitation of B and N atoms to form a highly continuous m-hBN film, as confirmed by cross-sectional transmission electron microscopy. m-hBN/graphene heterostructure on polyethylene terephthalate further demonstrates the significant improvement of gas barrier performance; a water vapor transmission rate of 0.01 g m−2 day is achieved, which is seven times lower than the previously reported value, while retaining a high transparency of 96.4% at a wavelength of 550 nm.

Influence of post-annealing on structural, optical and electrical properties of tin nitride thin films prepared by atomic layer deposition

Post-thermal annealing treatment is an effective process employing the thin film structure modifications and compositional properties. In this article, we present a detailed investigation and understanding of the changes in the phase, crystal structure, microstructure, and optoelectrical properties of tin nitride (SnNx) thin films. These were deposited by atomic layer deposition (ALD) followed by annealing at temperatures ranging from 300 to 550 °C. The results suggest that post-annealing significantly influences the properties of as-deposited ALD SnNx thin films at 150 °C. For instance, X-ray diffractometry (XRD) and transmission electron microscopy (TEM) results demonstrate that the as-deposited film predominantly forms an amorphous structure. After annealing up to 350 °C, the film retains its amorphous structure with a minor enhancement in crystallinity. The bonding state to reveal its phase was confirmed by X-ray photoelectron spectroscopy (XPS). The as-deposited film predominantly forms SnN bonding from Sn2+ states, and it is changed after annealing at 350 °C, where the fraction of Sn4+ from the Sn3N4 phase considerably increases. However, the XRD and TEM results do not distinguish the differences between as-deposited or 300 °C -annealed and 350 °C-annealed samples. After the annealing temperature is increased to 400 and 450 °C, both processes of crystallization into the mixed phase of hexagonal SnN and cubic Sn3N4, and their decomposition into metal Sn with simultaneous nitrogen release occur. At a further elevation of the annealing temperature (500 °C and beyond), a considerably distorted morphology and agglomeration of the as-deposited film structure was observed. This was due to the formation of island-like structures or droplets of metallic Sn by significantly releasing (or almost all) the nitrogen within the films. As the film properties vary upon annealing, spectroscopic ellipsometry (SE) was used to investigate the optical and electrical parameters of the as-deposited and annealed films. The optical band gap of the as-deposited film is 1.5 eV and remains unchanged up to 400 °C; it then increases to 1.9 eV at higher annealing temperatures. The electrical resistivity of the films decreases monotonically as the annealing temperature increases, which is attributed to the change in carrier concentration. The change in the optoelectronic properties can be associated with the change in crystallinity and escape of the nitrogen content connected with the change in stoichiometry.

Printable SnO2 cathode interlayer with up to 500 nm thickness-tolerance for high-performance and large-area organic solar cells

The printable electrode interlayer with excellent thickness tolerance is crucial for mass production of organic solar cells (OSCs) by solution-based print techniques. Herein, high-quality printable SnO2 films are simply fabricated by spin-coating or blade-coating the chemical precipitated SnO2 colloid precursor with post thermal annealing treatment. The SnO2 films possess outstanding optical and electrical properties, especially extreme thickness-insensitivity. The interfacial electron trap density of SnO2 cathode interlayers (CILs) are very low and show negligible increase as the thicknesses increase from 10 to 160 nm, resulting in slight change of the power conversion efficiencies (PCEs) of the PM6:Y6 based OSCs from 16.10% to 13.07%. For blade-coated SnO2 CIL, the PCE remains high up to 12.08% even the thickness of SnO2 CIL is high up to 530 nm. More strikingly, the large-area OSCs of 100 mm2 with printed SnO2 CILs obtain a high efficiency of 12.74%. To the best of our knowledge, this work presents the first example for the high-performance and large-area OSCs with the thickness-insensitive SnO2 CIL.

Light formation mechanisms induced by well-aligned sub-20-nm Ag quantum dots produced alongside patterned porous Si walls and bottoms

Sub-20-nm Ag nanoparticles created via sputtering were freely moved into preformed Si pores and were arranged along both wall and lower surfaces in etched Si layers via a post-thermal annealing treatment. The variously sized Ag quantum dots on the porous Si facilitate broadband visible emission via photo-generated enhanced luminescent effects, i.e., plasmonic effects of Ag nanoparticles by electron transfer from the Si-based matrix to the metallic Ag. The emission wavelengths and intensities, depending on the sizes of the Ag quantum dots, were determined by the degree of oxidation of the Si-based substrate such as Si, SiOx, and SiO2, according to different post-thermal annealing conditions. The morphological, microstructural, and optical evolution of Ag nanoparticles and Si pores were simply observed via side-cross-sectional scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and crystalline-controlled photoluminescence analyses, respectively. The origin of a new systematic luminescence mechanism based on energy-equilibria is also presented.

SnS2/Si vertical heterostructure for high-performance photodetection with large photocurrent and fast speed

It has attracted much research interest for the hot topic of photodetection application based on the two-dimensional (2D) heterostructures, owing to their higher light absorption and large separation efficiency of electron-hole pairs. However, the well-controlled growth with high-production and optoelectronic application of the heterostructures based on 2D materials still face great challenges. Photodetectors fabricated with the 2D SnS2/Si heterostructure have still not been well explored, although Si wafers have been proved to be an important substrate for novel optoelectronic application. Herein, the high-quality SnS2/Si heterostructure with large-size and uniform-thickness was prepared by using of a simple magnetron sputtering and post thermal annealing treatment in S atmosphere. The as-prepared SnS2/Si heterostructure exhibits the robust p-n contact and excellent diode rectification characteristic. The photodetector based on the heterostructure was then fabricated, which presents a reconfigurable switch behavior with a larger photocurrent up to 3.96 mA, a maximum detectivity of ~1011 Jones, a ultrafast response speed of 16 μs, and a broad bandwidth of 11.2 kHz. The highly crystalline and on-stoichiometry SnS2 films become a promising form factor to build the high-performance photodetectors. The SnS2/Si heterostructure devices open up an exciting field for novel optical detection application and optoelectronic memory devices.

Synthesis and characterization of Er2O3 nanorods and nanosheets

It is very important to develop a new synthetic route for lanthanide metal oxides with novel morphologies and having different fundamental properties and application performances. Here, we report Er2O3 nanorods and nanosheets prepared by a facile hydrothermal method followed by post-thermal annealing treatment. Thermal treatment of Er4O2(OH)8(HNO3) and Er2O5H4 was carried out to form the nanorods and nanosheets, respectively. Their physicochemical properties were evaluated by field-emission scanning electron microscopy, X-ray diffraction crystallography, high-resolution transmission electron microscopy, Fourier transform infrared (IR) spectroscopy, Ultraviolet-visible-near IR absorption spectroscopy, and X-ray photoelectron spectroscopy. The synthesis method and novel fundamental properties provide valuable information for the development of Er complexes and oxides.

Post-thermal annealing for enhancing photovoltaic performance of CdS/CdSe quantum dot co-sensitized TiO2 electrodes

In this paper, post-thermal annealing treatment is introduced to improve the photovoltaic performance of CdS/CdSe quantum dot (QD) co-sensitized TiO2 electrodes fabricated through successive ionic layer adsorption and reaction (SILAR) method. It has been found that post-thermal annealing could enhance the crystallinity of CdS and CdSe QDs obviously, increase the short-circuit current density (Jsc) and power conversion efficiency (PCE) of QD sensitized solar cells (QDSSCs) significantly. After annealing at 200 °C for 3 min, the Jsc and PCE of QDSSCs increase from 11.71 ± 0.23 mA cm−2 and 2.57 ± 0.05% to 12.99 ± 0.31 mA cm−2 and 2.86 ± 0.06%, respectively. With the post-thermal annealing temperature further increasing to 300 °C, the Jsc sharply increases to 15.75 ± 0.15 mA cm−2, but the PCE is almost unchanged, which has been attributed the sharply decrease of fill factor (FF). Electrochemical impedance spectroscopy measurement has demonstrated that the sharply increased FF originates from the increase of the resistance at TiO2/electrolyte interface when the post-thermal annealing treatment is 300 °C.

The role of non-solvent swelling in bulk hetero junction solar cells

The morphology and self-organization control of the active layer in solar cells based on poly(3-hexylthiophene): [6,6]-phenyl-C-61-buytyric acid methyl ester (P3HT:PCBM) is studied by applying a non-solvent swelling treatment, where an acetonitrile solution is applied on top of the active layer for 10min, followed by a spin-coating process to remove the non-solvent. After non-solvent swelling treatment, the optical absorption spectra for the active layer films indicated a red shift with developing features of P3HT, and X-ray diffraction (XRD) measurement data show the improvement of the effective interchain stacking of P3HT. Auger electron spectroscopy (AES) results clearly show that the inter-diffusion region between the active layer and cathode is enhanced. Atomic force microscopy (AFM) data show increasing surface roughness, which would lead to increased collection of charges and thus improved efficiency. When the non-solvent swelling method was combined with the post thermal annealing treatment, synergistic effects for the enhancement of power conversion efficiency were observed: post-thermal annealing only: 2.64%, non-solvent treatment only: 1.58%, non-solvent treatment and post-thermal annealing: 3.01% efficiency.

Charge carrier injection and transport associated with thermally generated cracks in a 6,13-bis(triisopropylsilylethynyl) pentacene thin-film transistor

We describe how the charge carrier injection and transport are influenced by thermal cracks in a 6,13-bis(triisopropylsilylethynyl) (TIPS) pentacene film in terms of the contact resistance and the channel resistance in a TIPS pentacene thin-film transistor (TFT). Through a post-thermal annealing (PTA) process at a certain temperature T a , the high structural order of TIPS-pentacene molecules is produced without thermal cracks, the carrier mobility of the TIPS pentacene TFT is maximized, and both the contact resistance and the channel resistance are minimized. Our quantitative description of the relationship between the PTA treatment and the interfacial resistance behavior would provide a useful basis for understanding the thermal stability and the electrical performance of a solution-processed organic TFT.

Highly Selective Cu Electrodeposition for Filling Through Silicon Holes

In this work, a copper plating formula that can directly and selectively fill the through silicon holes (TSHs) for 3D chip stacking packaging was developed. The copper plating technology reduced and simplified the process steps for fabricating through silicon vias (TSVs) and TSHs. The highly selectivity of copper fill in the TSHs also reduced the manufacture cost of 3D chip stacking packaging, because the copper plating technology reduced the loading of a post-copper chemical mechanical polishing (CMP) and did not need a post-thermal annealing treatment. The copper plating formula was very simple, just containing single organic additive.

The Effect of Thermal Treatment on Device Characteristic and Reliability for Sub-100-nm CMOSFETs

The effect of post-thermal annealing after halo implantation on device characteristic and reliability of sub-100-nm CMOSFETs was investigated. We found that the control of annealing time is more efficient than that of annealing temperature with respect to improving the hot-carrier-induced degradation. The best result of device performance and reliability was obtained by a post-thermal annealing treatment performed at medium temperatures (e.g., 900/spl deg/C) for a longer time (>1 min).

Deposition of LiTaO 3 thin films by pyrosol process

Lithium tantalate (LiTaO 3) thin films with submicron thickness were prepared by the “pyrosol” process based on the thermal decomposition on a heated substrate of an aerosol obtained by ultrasonic spraying. The crystalline orientations of the films versus different experimental parameters, like the substrate nature and the deposition temperature, were studied. Crystalline structure analysis of deposited materials showed that LiTaO 3 films crystallized successfully with single orientation on c-oriented sapphire substrates, without using post-thermal annealing treatment.