Conventional Thermal Annealing Research Articles

Sol-Gel Composites-Based Flexible and Transparent Amorphous Indium Gallium Zinc Oxide Thin-Film Synaptic Transistors for Wearable Intelligent Electronics

In this study, we propose the fabrication of sol-gel composite-based flexible and transparent synaptic transistors on polyimide (PI) substrates. Because a low thermal budget process is essential for the implementation of high-performance synaptic transistors on flexible PI substrates, microwave annealing (MWA) as a heat treatment process suitable for thermally vulnerable substrates was employed and compared to conventional thermal annealing (CTA). In addition, a solution-processed wide-bandgap amorphous In-Ga-Zn (2:1:1) oxide (a-IGZO) channel, an organic polymer chitosan electrolyte-based electric double layer (EDL), and a high-k Ta2O5 thin-film dielectric layer were applied to achieve high flexibility and transparency. The essential synaptic plasticity of the flexible and transparent synaptic transistors fabricated with the MWA process was demonstrated by single spike, paired-pulse facilitation, multi-spike facilitation excitatory post-synaptic current (EPSC), and three-cycle evaluation of potentiation and depression behaviors. Furthermore, we verified the mechanical robustness of the fabricated device through repeated bending tests and demonstrated that the electrical properties were stably maintained. As a result, the proposed sol-gel composite-based synaptic transistors are expected to serve as transparent and flexible intelligent electronic devices capable of stable neural operation.

Effects of temperature gradients on magnetic anisotropy of SmCo based films

The magnetic anisotropy of SmCo-based permanent magnetic thin films are generally controlled by introducing buffer layer or heating substrate. However, the design for the multi-layer thin film system is complicated and the thickness of SmCo is limited due to a short range of interfacial stress/strain between the buffer layer and SmCo layer. In this work, the effects of temperature gradients, generated by RTP (rapid thermal process), on the magnetic anisotropy of the SmCo-based films were systematically investigated. The results show that the as-deposited films exhibit amorphous state. The out-of-plane coercivity of RTP-treated films is strongly correlated with the heating rate, and its optimum value (2810 Oe) is larger than that of the CTA (conventional thermal annealing) treated films (1670 Oe). For the RTP-treated films, the intensity of characteristic diffraction peaks for in-plane oriented SmCo5 (200) and Sm2Co17 (300) decreases, together with reducing the roughness. Besides, the grain size is finer and the contrast of magnetic domains becomes stronger for the RTP-treated films due to that the easy axis of SmCo5/Sm2Co17 phase gradually changes from in-plane to out-of-plane direction. It is suggested that the RTP treatment with a shorter annealing time has beneficial effects on obtaining finer microstructure and improving the out-of-plane magnetic anisotropy of the SmCo-based films. This work provides a novel way to control the magnetic anisotropy via annealing temperature gradients for permanent magnetic thin films, compared with conventional methods, to induce the magnetic anisotropy.

Enhancement in the extinction ratio of a wire grid polarizer in the mid-wavelength infrared range via hot electron diffused cold-annealing

Theoretical and experimental investigations were performed on the fabrication and polarization property enhancement of a single-layer Au grating serving as a wire grid polarizer (WGP) in the mid-wavelength infrared (MWIR) range. Femtosecond laser (FSL) annealing was performed to overcome the performance limitations of the WGP fabricated by nanotransfer printing (NTP), and the results were compared with those of the conventional thermal annealing methods using scanning electron microscopy, atomic force microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. Consequently, the extinction ratio of the WGP annealed with FSL reached up to 1378 (∼31 dB) in the 3–5 μm wavelength range, which corresponds to a 2.18-fold improvement over the non-annealed WGP. This result suggests that it is possible to manufacture MWIR WGPs at a low cost and over large areas through a simple NTP and FSL annealing process, ultimately yielding WGPs with improved performances.

Effects of the sequential implantation of Mg and N ions into GaN for p-type doping

The sequential implantation of Mg and N ions into GaN was investigated using conventional rapid thermal annealing and ultra-high-pressure annealing (UHPA). In cathodoluminescence, the green luminescence related to nitrogen vacancies (VNs) was mostly suppressed at the Mg/N ratio of 0.5–1.0, whereas the donor–acceptor pair (DAP) emission as a signature of Mg acceptors was maintained high. The excess N implantation reduced the DAP emission through the formation of nonradiative recombination centers. The combined process of optimal Mg/N implantation and UHPA at 1673 K improved ohmic contacts by increasing Mg concentration and suppressing VNs near the surface.

Supporting plasma processes for fabrication of n-doped nano-crystalline silicon thin film on low-cost glass substrates

Nano-crystalline silicon is an excellent material for applications in the optoelectronics industry. This intermediate material combines both the advantages of amorphous and crystalline silicon. However, the typical fabrication process of nano-crystalline silicon previously required high-quality substrates such as quartz or silicon wafers, which limited its potential applications. Recently, plasma treatments have been recognized as the most efficient and customizable methods for transforming materials. In this study, corona plasma was used to treat the low-cost glass substrates to improve their adhesion to silicon thin films. It allowed the film to become more uniform with a surface roughness of less than 10% at the thickness of about 1 μm. The conventional thermal annealing process was replaced by a high-power hydrogen plasma process, which does not cause harmful effects on the glass substrates and stimulates the amorphous-crystalline phase transition. The increasing of the crystalline fraction, which is known as the order of arrangement of silicon atoms network, affects the doped concentration as well as the electrical properties of the nc-Si:H thin films. The resulting n-doped nano-crystalline silicon thin film has a crystalline fraction of 32.8%, corresponding to a sheet resistance of 104 Ω/square.

High-performance solution-processed flexible Cu2O photodetector via UV-irradiation

Solution processing of metal oxide semiconductors (MOS) is widely used for electronic and optoelectronic applications. However, the high-temperature annealing process that is required for device-quality films is incompatible with a flexible substrate because plastics can be thermally damaged. This study fabricates a p-type Cu2O flexible photodetector (PD) with a metal-semiconductor-metal structure on a polyethylene terephthalate (PET) substrate by irradiating a preheated precursor film with ultraviolet (UV) light. High-quality Cu2O crystals are formed on PET substrates by the charge transfer transition that is excited by the UV-irradiation at room temperature. An extremely high photo-to-dark current ratio (PDCR) of 1590 is achieved for a solution-processed Cu2O flexible PD. This flexible PD exhibits a relatively fast photoresponse (~0.2 s) and folds reproducibly after repeated bending for 500 cycles. This process does not require conventional high-temperature thermal annealing and is applicable to other solution-processed MOS, particularly those that are used for flexible electronic applications.

Low-temperature annealing of 2D Ti3C2Tx MXene films using electron wind force in ambient conditions

Two-dimensional transition metal carbides and nitrides, known as MXenes, are layered materials with unique functionalities which make them suitable for applications such as energy storage devices, supercapacitors, electromagnetic interference shielding, and wireless communications. Since they are wet-processed, MXenes need annealing to improve their electrical conductivity. The extent of annealing highly depends on temperature; however, higher temperatures can also impact the resulting phases and structure. In this study, we present a non-thermal annealing process utilizing an electron wind force (EWF) method in ambient conditions. This process is demonstrated on freestanding Ti3C2Tx films, where we show up to 70% decrease in resistivity at temperatures below 120 °C compared to conventional thermal annealing methods. MXene structures before and after annealing are analyzed using Raman spectroscopy and ex situ and in situ X-ray diffraction. Surface terminations and intra-flake defects modification in Ti3C2Tx layers after EWF annealing impart better electrical conductivity to MXene film than the non-annealed films.

Investigation of the effect of annealing on the structural, morphological and optical properties of RF sputtered WO3 nanostructure

In this study, we focused on examining the effect of annealing on the structural, morphological, and optical properties of the tungsten oxide (WO3) nanostructures. WO3 nanostructure deposited on n-type Si substrate using the radio frequency (RF) magnetron sputtering system. The WO3 nanostructure was divided into 6 parts. 5 samples except as-deposited samples were individually annealed at various temperatures ranging from 300 °C to 700 °C (by step 100 °C) in a conventional thermal annealing furnace (CTA) for 1 h. The stoichiometry of the as-deposited WO3 was determined by SEM-EDS and XPS measurements. Structural, morphological, and optic properties of the as-deposited and different annealed temperatures WO3 nanostructures were characterized by XRD, AFM, Uv–Vis and PL measurements. The effects of annealing on material analysis and properties were reported with a comparative study. It has been reported that the annealed WO3 nanostructure can be preferred as an effective material for device applications.

Flash lamp annealing processing to improve the performance of high-Sn content GeSn n-MOSFETs

This paper describes the use of flash lamp annealing (FLA) to fabricate high-Sn content GeSn n-MOSFETs. We exploit FLA processing for both impurity activation and for the solid-phase growth (SPG) of the GeSn channel. High-Sn incorporation of up to 12% is achieved by overcoming the solid-solubility limit of Sn in Ge (1%), and high-quality n+-source/drain junctions were obtained by P implantation and subsequent FLA. Consequently, we achieved well-behaved transistor operation of the SPG-Ge0.88Sn0.12 n-MOSFETs, with an on/off current ratio one order of magnitude higher than for conventional rapid thermal annealing processing.

Implementation of High‐Performance Solution‐Processed Amorphous Indium–Gallium–Zinc–Oxide Thin‐Film Transistors with Low Charge Traps by Microwave Heat Treatment of Low Thermal Budget

Herein, high‐performance solution‐processed amorphous indium–gallium–zinc–oxide (a‐IGZO) thin‐film transistors (TFTs) with low trap densities due to post‐deposition annealing (PDA) are processed with a low‐thermal‐budget microwave (MW) heat treatment. To verify the MW effectiveness, the composition ratio of a‐IGZO thin films and the electrical characteristics of TFTs prepared by conventional thermal annealing (CTA) are compared. An X‐ray photoelectron spectroscopy (XPS) analysis reveals that MW annealing (MWA) improves the film quality more effectively than CTA. a‐IGZO TFTs treated by MWA or CTA are fabricated to evaluate their electrical characteristics. MWA is more effective than CTA in improving the performance, such as hysteresis, subthreshold swing (SS), field effect mobility (μ FE), and on/off current ratio (I on/I off). MWA provides lower interfacial trap density (D it) and volume trap density (N t) than CTA. To evaluate instability, the threshold voltage (V TH) shift is monitored using positive and negative gate‐bias stress tests. MWA demonstrates better reliability than CTA. In conclusion, high‐performance solution‐based a‐IGZO TFTs can be implemented by lowering the charge traps in the a‐IGZO channel using MWA.

Functionalization of Zinc Oxide Nanoflowers with Palladium Nanoparticles via Microwave Absorption for Room Temperature-Operating Hydrogen Gas Sensors in the ppb Level.

Microwave-assisted functionalization of zinc oxide nanoflowers (ZnO NFs) with palladium nanoparticles (Pd NPs) is demonstrated to realize high-performance chemiresistive-type hydrogen (H2) gas sensors operating at room temperature (RT). The developed gas sensors exhibit a high response of up to 70% at 50 ppm and a theoretical detection limit of 10 ppb. The formation of ZnO NFs with an enhanced specific surface area and their functionalization with Pd NPs are investigated through various characterizations. Furthermore, the optimization of microwave absorption upon the structural incorporations between nanostructures (NF-NPs) is investigated for solution-based functionalization at low temperatures (below 120 °C) for short process times (within 1 min), compared to the conventional thermal annealing at 250 °C for 1 h. Highly sensitive and selective ZnO-based gas sensors enabling the detection of H2 gas molecules at 300 ppb concentration at RT exhibit a short response/recovery time of below 3 min and a good selectivity toward different gases including nitric oxide, carbon monoxide, and oxygen. The successful functionalization of nanostructured metal oxide semiconductors (MOSs) with metal NPs via effective and practical microwave absorption enhances the potential on highly sensitive and selective chemiresistive-type MOS-based gas sensors operating at RT without additional heaters or photogenerators.

Thermal Damage-Free Microwave Annealing with Efficient Energy Conversion for Fabricating of High-Performance a-IGZO Thin-Film Transistors on Flexible Substrates.

In this study, we applied microwave annealing (MWA) to fabricate amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) without thermal damage to flexible polyimide (PI) substrates. Microwave energy is highly efficient for selective heating of materials when compared to conventional thermal annealing (CTA). We applied MWA and CTA to a-IGZO TFTs on PI substrate to evaluate the thermal damage to the substrates. While the PI substrate did not suffer thermal damage even at a high power in MWA, it suffered severe damage at high temperatures in CTA. Moreover, a-IGZO TFTs were prepared by MWA at 600 W for 2 min, whereas the same process using CTA required 30 min at a temperature of 300 °C, which is a maximum process condition in CTA without thermal damage to the PI substrate. Hence, MWA TFTs have superior electrical performance when compared to CTA TFTs, because traps/defects are effectively eliminated. Through instability evaluation, it was found that MWA TFTs were more stable than CTA TFTs against gate bias stress at various temperatures. Moreover, an MWA TFT-constructed resistive load inverter exhibited better static and dynamic characteristics than the CTA TFT-constructed one. Therefore, MWA is a promising thermal process with efficient energy conversion that allows the fabrication of high-performance electronic devices.

Observation of ordered microphase separation of block copolymer micellar thin films under argon-plasma radiation

Block Copolymer (BCP) self-assembly has shown promise as a next generation nanolithography technology as their phase separation at a nanometre scale can overcome the limitations of conventional lithography. Here, we report on using an alternative method to conventional thermal and solvent annealing by exposing as-cast micellar polystyrene-b-poly(ethylene oxide) (PS-b-PEO) thin film to a mild argon plasma. Resulting films show controllable perpendicular and parallel (to the surface plane) orientations of a hexagonal phase forming PEO, depending on the morphology of the initial micelle shape. The ability to define orientation is a critical advantage because complex solvent or substrate control is usually needed. This method is a fast process, that could help to reduce thermo-solvent annealing time (hours) to few seconds, while allowing phase separation on large and industrial substrates. Further, etching is also realized during the plasma exposure. We discuss the balance between the energy input of the argon plasma leading to large-scale surface reorganisation, and the possible damage of the surface due to cross-linking and/or etching.

Protection of isolated and active regions in AlGaN/GaN HEMTs using selective laser annealing* *Project supported by the National Natural Science Foundation of China (Grant Nos. 51577169 and 51777187), the National Key Research and Development Program of China (Grant No. 2017YFB0402804), and the “Science and Technology Innovation 2025” Major Program of Ningbo (Grant No. 2018B10098).

AlGaN/GaN high-electron-mobility transistors with Au-free ohmic contacts are fabricated by selective laser annealing and conventional rapid thermal annealing. The current transport mechanism of ohmic contacts is investigated. High-temperature annealing can be avoided in the isolated region and the active region by selective laser annealing. The implanted isolation leakage current is maintained 10−6 mA/mm even at 1000 V after selective laser annealing. On the contrary, high-temperature annealing will cause obvious degradation of the isolation. The morphology of AlGaN surface is measured by atomic force microscope. No noticeable change of the AlGaN surface morphology after selective laser annealing, while the root-mean-square roughness value markedly increases after rapid thermal annealing. The smaller frequency dispersion of capacitance–voltage characteristics confirms the lower density of surface states after selective laser annealing. Thus, dynamic on-resistance is effectively suppressed.

Comparison of Thermal Annealing versus Hydrothermal Treatment Effects on the Detection Performances of ZnO Nanowires.

A comparative investigation of the post-electroplating treatment influence on the gas detecting performances of single ZnO nanorod/nanowire (NR/NW), as grown by electrochemical deposition (ECD) and integrated into nanosensor devices, is presented. In this work, hydrothermal treatment (HT) in a H2O steam and conventional thermal annealing (CTA) in a furnace at 150 °C in ambient were used as post-growth treatments to improve the material properties. Herein, the morphological, optical, chemical, structural, vibrational, and gas sensing performances of the as-electrodeposited and treated specimens are investigated and presented in detail. By varying the growth temperature and type of post-growth treatment, the morphology is maintained, whereas the optical and structural properties show increased sample crystallization. It is shown that HT in H2O vapors affects the optical and vibrational properties of the material. After investigation of nanodevices based on single ZnO NR/NWs, it was observed that higher temperature during the synthesis results in a higher gas response to H2 gas within the investigated operating temperature range from 25 to 150 °C. CTA and HT or autoclave treatment showed the capability of a further increase in gas response of the prepared sensors by a factor of ∼8. Density functional theory calculations reveal structural and electronic band changes in ZnO surfaces as a result of strong interaction with H2 gas molecules. Our results demonstrate that high-performance devices can be obtained with high-crystallinity NWs/NRs after HT. The obtained devices could be the key element for flexible nanoelectronics and wearable electronics and have attracted great interest due to their unique specifications.

Low-Fluorine Ba-Deficient Solutions for High-Performance Superconducting YBCO Films

High-performing superconducting YBa2Cu3O7–x (YBCO) films are fabricated by a chemical solution deposition methodology through novel barium-deficient low-fluorine solutions. The precursor solutions, distinguished for being straightforward, inexpensive and eco-friendly, allow us to reduce the growing temperature of YBCO down to 750 °C. We investigated the influence of the growing temperatures on both the microstructure and superconducting properties of YBCO films by using conventional thermal annealing and flash-heating approaches. A clear correlation between the growing temperature (Tg) and the superconducting performance of the films was obtained with improved performances observed at low Tg.

Photocatalytic Hydrogen Generation from Water‐Annealed TiO2 Nanotubes with White and Grey Modification

AbstractIn recent years, photocatalytic reactions on anodic TiO2 nanotubes have been intensively investigated. In order to show photocatalytic activity, anodically formed nanotubes need to be crystallized to anatase. This is conventionally done by thermal annealing in air at temperatures 400–600 °C. Recently, a so‐called “water annealing” treatment has been reported to be effective to also create a highly active form for photocatalysis. Here we report on the feasibility of using a water annealing treatment of TiO2 nanotubes to create a photocatalyst for H2 production that is as active as conventional thermal annealing. If the water‐annealed samples are additionally hydrogenated to a so‐called “grey” modification, a further significant improvement of the photocatalytic activity for H2 evolution can be achieved – this without the use of any noble metal co‐catalyst. A combination of water annealing, thermal annealing, followed by hydrogenation can deliver a H2 generation activity that is more than five times higher than that achieved by thermal annealing of anodic TiO2 nanotubes.

Кинетические закономерности синтеза литий-цинкового феррита в условиях нагрева пучком электронов

The paper considers kinetic studies lithium-zinc ferrite synthesis under heating by high-energy electron beam of mixtures of the initial Fe2O3 – Li2CO3 – ZnO reagents of different prehistory. We used samples of bulk density and compressed in hydraulic press. Radiation-thermal synthesis of samples was carried out an ILU-6 pulsed electron accelerator by heating of high-energy electrons with 2.4 MeV energy. Was spending heating to 600, 700, 750 °C and kept at 0 to 120 minutes. Formation of ferrite in conventional thermal annealing at similar temperature and time conditions was studied for comparison. Characterized method for studying synthesized samples was X-ray diffraction analysis. It is found that the rate of ferrite formation depends on both the heating method and the density of the initial mixture. It is shown that heating the mixture with an electron beam significantly accelerates the process of obtaining ferrite, which is manifested in a decrease of the kinetic parameters of ferrite synthesis. The increase the rate of ferrite formation under high-energy electron irradiation is due to a significant decrease in activation energy of synthesis process and decrease in pre-exponential multiplier in temperature dependence.

Improved Contact Resistivity and Transconductance for Sub-10 nm FinFET Technology by Laser-Induced Contact Silicide

Ultra-violet laser thermal annealing (LTA) is proposed to form contact TiSix for sub-10 nm FinFETs. Compared to conventional rapid thermal annealing (RTA), LTA process leads to reduced total series resistance (RTotal) by 10.1∼16.1% and 13.0∼15.3% which corresponds to enhanced transconductance (gm) by 7.7∼9.8% and 5.9∼9.0% for N-/P-FinFETs respectively due to improved contact resistivity (ρc) by 69% arising from more orderly local Ti-Si bonds and smoother TiSix/Si interface. There is also no concern of LTA process in terms of comparable off-state/junction leakage and reliability by hot carrier stress. In addition, LTA is VLSI-compatible without adding any process complexity. These promising properties enable LTA to further unleash the performance of FinFETs.

Reliability aspects of ferroelectric TiN/Hf0.5Zr0.5O2/Ge capacitors grown by plasma assisted atomic oxygen deposition

The reliability of Hf0.5Zr0.5O2 (HZO) metal–ferroelectric–semiconductor capacitors grown by plasma-assisted atomic oxygen deposition on Ge substrates is investigated with an emphasis on the influence of crystallization annealing. The capacitors show very weak wake-up and imprint effects, allowing reliable operation in excess of 10 years, which is attributed partly to the clean, oxide-free Ge/HZO bottom interface. The weak temperature dependence and the observed asymmetries between polarization up and down states and between positive and negative coercive voltage shifts lead to the conclusion that imprint is controlled by carrier injection at the top electrode interface. The latter mechanism is associated with trapping at interfacial oxygen-vacancy defects. On the other hand, using ultrafast (millisecond) flash annealing improves the leakage current by at least an order of magnitude and the endurance by a factor of 3 compared to conventional rapid thermal annealing, which makes them suitable for low power nonvolatile memory applications where (ultra)thin HZO is an essential requirement.