Search

The vast high entropy alloy (HEA) composition space is promising for discovery of new material phases with unique properties. This study explores the potential to achieve rare‐earth‐free high magnetic anisotropy materials in single‐phase HEA thin films. Thin films of FeCoNiMnCu sputtered on thermally oxidized Si/SiO2 substrates at room temperature are magnetically soft, with a coercivity on the order of 10 Oe. After post‐deposition rapid thermal annealing (RTA), the films exhibit a single face‐centered‐cubic phase, with an almost 40‐fold increase in coercivity. Inclusion of 50 at.% Pt in the film leads to ordering of a single L10 high entropy intermetallic phase after RTA, along with high magnetic anisotropy and 3 orders of magnitude coercivity increase. These results demonstrate a promising HEA approach to achieve high magnetic anisotropy materials using RTA. [ABSTRACT FROM AUTHOR]

We report herein the analysis of the properties of copper(I) oxide thin films deposited by an optimized ammonium-free successive ion layer adsorption and reaction (SILAR) technique. The Cu2O thin film deposition process was carried out at room temperature using copper acetate monohydrate, sodium citrate as complexing agent, and hydrogen peroxide as precursors of copper and oxygen ions, respectively. The harmless and easy-to-handle sodium citrate replaces the volatile NH4OH commonly employed as complexing agent in the SILAR technique for the deposition of metal oxide thin films. The optical, structural, morphological, and electrical properties of the as-deposited Cu2O thin films were studied as a function of the number of cycles during deposition, as well as their modifications produced by the effect of rapid thermal annealing (RTA) in vacuum in a temperature range of 200–250°C for 1 min, 3 min, and 5 min. The as-deposited thin films had cubic crystalline structure corresponding to the Cu2O phase as determined by x-ray diffraction (XRD), with a direct energy bandgap of 2.43–2.51 eV depending on the number of cycles, and electrical resistivity of the order of 103 Ω cm. The XRD and x-ray photoelectron spectroscopy (XPS) analysis of the Cu2O thin films treated by RTA demonstrated an increase of the crystal size with time and temperature of the RTA and reduction effects from Cu2+ to Cu1+ oxidation states. On the other hand, the RTA treatments also decreased their energy bandgap to 2.38 eV and electrical resistivity to 102 Ω cm. The high energy bandgap values of the Cu2O thin films were attributed to quantum confinement effects produced by their small crystal size in the range of 3.6–8.6 nm. [ABSTRACT FROM AUTHOR]

This paper presents an investigation into the influence of repeating cycles of hydrothermal growth processes and rapid thermal annealing (HT+RTA) on the properties of CuO thin films. An innovative hydrothermal method ensures homogeneous single-phase films initially. However, their electrical instability and susceptibility to cracking under the influence of temperature have posed a challenge to their utilization in electronic devices. To address this limitation, the HT+RTA procedure has been developed, which effectively eliminated the issue. Comprehensive surface analysis confirmed the procedure’s ability to yield continuous films in which the content of organic compounds responsible for the formation of cracks significantly decreases. Structural analysis underscored the achieved improvements in the crystalline quality of the films. The implementation of the HT+RTA procedure significantly enhances the potential of CuO films for electronic applications. Key findings from Kelvin probe force microscopy analysis demonstrate the possibility of modulating the work function of the material. In addition, scanning capacitance microscopy measurements provided information on the changes in the local carrier concentration with each repetition. These studies indicate the increased usefulness of CuO thin films obtained from the HT+RTA procedure, which expands the possibilities of their applications in electronic devices.

Zinc oxide (ZnO) is a wide bandgap semiconductor that holds significant potential for various applications. However, most of the native point defects in ZnO like Zn interstitials typically cause an n-type conductivity. Consequently, achieving p-type doping in ZnO is challenging but crucial for comprehensive applications in the field of optoelectronics. In this work, we investigated the electrical and optical properties of ex situ doped p-type ZnO films. The p-type conductivity has been realized by ion implantation of group V elements followed by rapid thermal annealing (RTA) for 60 s or flash lamp annealing (FLA) on the millisecond time scale in nitrogen or oxygen ambience. The phosphorus (P)-doped ZnO films exhibit stable p-type doping with a hole concentration in the range of 1014 to 1018 cm−3, while antimony (Sb) implantation produces only n-type layers independently of the annealing procedure. Microstructural studies of Sb-doped ZnO show the formation of metallic clusters after ms range annealing and SbZn-oxides after RTA. [ABSTRACT FROM AUTHOR]

Abstract The vast high entropy alloy (HEA) composition space is promising for discovery of new material phases with unique properties. This study explores the potential to achieve rare‐earth‐free high magnetic anisotropy materials in single‐phase HEA thin films. Thin films of FeCoNiMnCu sputtered on thermally oxidized Si/SiO2 substrates at room temperature are magnetically soft, with a coercivity on the order of 10 Oe. After post‐deposition rapid thermal annealing (RTA), the films exhibit a single face‐centered‐cubic phase, with an almost 40‐fold increase in coercivity. Inclusion of 50 at.% Pt in the film leads to ordering of a single L10 high entropy intermetallic phase after RTA, along with high magnetic anisotropy and 3 orders of magnitude coercivity increase. These results demonstrate a promising HEA approach to achieve high magnetic anisotropy materials using RTA.

Buckypaper (BP), a flexible and porous material, exhibits photovoltaic properties when exposed to light. In this study, we employed radio frequency (RF) sputtering of zinc oxide (ZnO) followed by rapid thermal annealing to enhance the photovoltaic response of BP. We investigated the impact of various sputtering parameters, such as the gas flow ratio of argon to oxygen and deposition time, on the morphology, composition, resistivity, and photovoltaic characteristics of ZnO-modified BP. Additionally, the photovoltaic performance of the samples under different illumination modes and wavelengths was compared. It was found that optimal sputtering conditions—argon to oxygen flow ratio of 1:2, deposition time of 20 min, and power of 100 watts—resulted in a ZnO film thickness of approximately 45 nanometers. After annealing at 400 °C for 10 min, the ZnO-modified BP demonstrated a significant increase in photocurrent and photovoltage, along with a reduction in resistivity, compared to unmodified BP. Moreover, under gradient illumination, the ZnO-modified BP exhibited a photovoltage enhancement of 14.70-fold and a photocurrent increase of 13.86-fold, compared to uniform illumination. Under blue light, it showed a higher photovoltaic response than under other colors. The enhancement in photovoltaic response is attributed to the formation of a Schottky junction between ZnO and BP, an increased carrier concentration gradient, and an expanded light absorption spectrum. Our results validate that ZnO sputtering followed by annealing is an effective method for modifying BP for photovoltaic applications such as solar cells and photodetectors. [ABSTRACT FROM AUTHOR]

Dopant‐selective electrochemical etching (ECE) of gallium nitride (GaN) results in well‐defined porous layers with tunable refractive index, which is extremely interesting for integrating photonic components into nitride technology. Herein, the impact of nitrogen implantation with and without subsequent rapid thermal annealing (RTA) on the porosification process of highly n‐doped GaN ([Si] 3 × 1019 cm−3) is investigated. Implantation is expected to compensate the donors of the n‐GaN layer to spatially suppress porosification during ECE. Optical transmission, electrochemical capacitance–voltage, and X‐Ray diffractometry of as‐grown and as‐implanted GaN suggest successful compensation of n‐dopants. Cross‐sectional scanning electron microscopy reveals the presence of mesopores (diameter 2–50 nm) after ECE of the as‐grown n‐GaN. In the case of implanted n‐GaN, it is found that ECE results in macropores (diameter > 50 nm), which can be suppressed by an intermediate RTA step. The implanted and annealed n‐GaN layers solely exhibit mesopores at the top and bottom, while the intermediate region remains unimpaired. Chronoamperometry and gravimetry provide additional insight and confirm the presence of macro‐ and mesopores in samples without and with RTA, respectively. The results demonstrate a successful implementation of etch‐resisting subsurface layers, which are required for 3D refractive index engineering in porous GaN. [ABSTRACT FROM AUTHOR]

By adjusting the rising time in annealing ferroelectric HfO2-based films, the grain size of the film can be controlled. In this study, we found that increasing the rising time from 10 to 30 s at an annealing temperature of 700 °C in N2 atmosphere resulted in improved ferroelectric switching speed. This is because the larger grain size reduces the internal resistance components, such as the grain bulk resistance and grain boundary resistance, of the HZO film. This in turn lowers the overall equivalent resistance. By minimizing the RC time constants, increasing the grain size plays a key role in improving the polarization switching speed of ferroelectric films. [ABSTRACT FROM AUTHOR]

Single-crystal c-Ge plates implanted with Ag+ ions with an energy of E = 30 keV, current density of the ion beam J = 5 μA/cm2 and a dose of D = 2.5 × 1016 ions/cm2 were subjected to rapid thermal annealing by single light pulses of various durations from 1 up to 9.5 s. By scanning electron microscopy and optical reflection spectroscopy measurements it was shown that after ion implantation an amorphous porous Ag:PGe layer of spongy structure, consisting of Ge nanowires, is formed on the surface of c-Ge substrates. It was found that the annealing with an increase in the pulse duration up to 5 s successively leads to an increase in the Ge nanowire diameters from 26 to 35 nm. With longer pulses, the porous Ag:PGe structure is destroyed and Ag evaporates from the implanted layers. [ABSTRACT FROM AUTHOR]

Pulsed laser hyperdoping is widely investigated as an effective method for expanding the infrared absorption of silicon. Prior to further device fabrication, thermal treatment is commonly applied to hyperdoped silicon to repair lattice defects and activate dopants. However, it is observed that thermal treatment adversely affects the infrared absorption of hyperdoped silicon, and the underlying mechanisms remain incompletely understood. Herein, zinc‐hyperdoped silicon (Si:Zn) is prepared using vacuum magnetron sputtering combined with femtosecond laser pulses, and the mechanisms of the reduction in infrared absorption during conventional annealing of Si:Zn samples are investigated. The diffusion of zinc and its precipitation as zinc clusters in silicon are observed during the annealing process, leading to a decrease in the concentration of zinc dopants within the silicon lattice and consequent attenuation of infrared absorption. Building upon this understanding, the approach of short timescale annealing subjected to infrared rapid thermal annealing furnace is proposed to be employed as a method to mitigate the adverse effects of zinc transitional precipitation, resulting in enhancement of the performance of Si:Zn optoelectronic devices. [ABSTRACT FROM AUTHOR]

Porous carbon materials have increasingly drawn interest for applications ranging from supercapacitive energy storage to bioengineering. However, a simple and scalable fabrication process of such materials, employing low‐cost chemical compounds without sacrificing morphological and chemical control, remains lacking. Here, a novel, rapid, continuous bottom‐up strategy for synthesizing structurally tunable porous carbon network films on insulating and conductive substrates is reported. By employing rapid thermal annealing (RTA) of a commercial polyacrylonitrile‐based blend, simultaneous phase separation and thermal crosslinking are induced, effectively freezing the structure. Subsequent burning of degradable components generates a porous carbon framework (d¯pore${\bar{d}}_{{\mathrm{pore}}}$ ≈ 360 to 700 nm) doped with nitrogen and oxygen atoms. Introducing a boron‐containing reagent in the precursor solution enables boron doping and pore size reduction as small as 20 nm, enhancing materials' performance. The direct fabrication of micro‐supercapacitors on stainless steel substrates is demonstrated, achieving an areal capacitance of 12.7 mF cm−2 at 50 mV s−1, with ≈98% retention after 10 000 charge/discharge cycles. The benefit of boron doping is further highlighted for wound healing applications. Because RTA is already an established industrial method, this platform directly facilitates the synthesis of functional porous heteroatom‐doped carbon structures using commercial polymers and dopants for various applications. [ABSTRACT FROM AUTHOR]

In recent years, the growing demand for renewable energy sources has led to an increased interest for searching some ways to improve the factors affecting the power conversion efficiency (PCE) of solar cells. Silicon solar cells technology has reached a high level of development in relation to efficiency and stability. This study presents the effect of rapid thermal annealing (RTA) at different annealing temperatures and times on the characteristics of solar cells fabricated by Nd:YAG laser doping of p-type crystalline silicon wafer with phosphorus dopant to a depth of 3.7 µm and concentration of approximately 1020 cm−3. The conversion efficiency (η) was studied before and after rapid thermal annealing, which increased from 3.67 to 12.8% after RTA at 1073 K for 6 s. The large increase of the short-circuit current density (JSC) and open-circuit voltage (VOC) indicated an enhanced absorption coefficient, reduced lattice defects, and a redistribution of impurities, which improved the electrical activity of impurities. Furthermore, the results demonstrated increased minority carrier lifetime, diffusion length, and improved responsivity after rapid thermal annealing. Solar cells annealed at 1073 K for 6 s exhibited the best photovoltaic properties. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) is a wide bandgap semiconductor that holds significant potential for various applications. However, most of the native point defects in ZnO like Zn interstitials typically cause an n-type conductivity. Consequently, achieving p-type doping in ZnO is challenging but crucial for comprehensive applications in the field of optoelectronics. In this work, we investigated the electrical and optical properties of ex situ doped p-type ZnO films. The p-type conductivity has been realized by ion implantation of group V elements followed by rapid thermal annealing (RTA) for 60 s or flash lamp annealing (FLA) on the millisecond time scale in nitrogen or oxygen ambience. The phosphorus (P)-doped ZnO films exhibit stable p-type doping with a hole concentration in the range of 1014 to 1018 cm−3, while antimony (Sb) implantation produces only n-type layers independently of the annealing procedure. Microstructural studies of Sb-doped ZnO show the formation of metallic clusters after ms range annealing and SbZn-oxides after RTA.

The current research demonstrates the modification of the wetting behavior and mechanical features as well as structure and morphology of Fe3Si films created via facing target sputtering by the rapid thermal annealing (RTA) with the set RTA temperatures (TRTA) of 200, 400, 600, and 800 °C. Following the RTA process, the crystallinity of Fe3Si developed under 400 °C or below. At the 600 °C and 800 °C TRTA, new crystal orientations emerged for FeSi and then β-FeSi2, respectively. Together with composition results, the Fe3Si films were proven to change into FeSi and then FeSi2 under a high TRTA regime. At temperatures of 600 °C and 800 °C, large crystallites, including the scraggly interface, were observed. The root-mean-square roughness roughened slightly according to the RTA process at TRTA of 600 °C or above. The hydrophobic properties of the Fe3Si film surfaces became hydrophilic after the RTA procedure at a TRTA value above 400 °C. The hardness value of the Fe3Si films evidently increased through RTA at 600 °C and 800 °C. Thus, above 400 °C, the RTA process significantly alters the physical features of as-created Fe3Si films.

Autodoping is a well-known phenomenon of unwanted dopant transfer in silicon epitaxy process. In this work, we discovered boron lateral autodoping in normal rapid thermal process (RTP) and used it to controllably form shallow junctions for device fabrication. The redeposition of boron from the gas phase to the solid surface was identified to be the limiting step of the boron incorporation into the undoped silicon area in the RTP process. At a given RTP temperature, boron autodoping could be increased by elevating the concentration of the boron source or enhancing the evaporation coefficient. Extending the annealing time can substantially improve the uniformity of the boron concentration in the gas phase, thus reducing the pattern dependence of the autodoping results. In addition, the autodoping process also avoids the traps and defects induced by ion implantation. Therefore, the described mechanism holds great promise for shallow junction formation in selectively patterned area with low cost. [ABSTRACT FROM AUTHOR]

Finely dispersed Y2O3:Eu, Y2Si2O7:Eu, YF3:Ce and YF3:Eu luminescent phosphors are synthesized using a hydrothermal method. A process is developed for obtaining Y2O3:Eu phosphors with a reduced particle size by hydrothermal precipitation with the addition of an inert finely dispersed filler (Aerosil) followed by rapid thermal annealing (RTA). Another process is suggested for the synthesis of finely dispersed Y2Si2O7:Eu phosphor via hydrothermal precipitation followed by microwave annealing. The effect of the synthesis conditions on the properties of YF3:Ce and YF3:Eu nanosized phosphors is studied and hydrothermal processing conditions were determined so as to provide the adjustment of their luminescence spectra due to the variation of the activator valency (Eu3+/Eu2+ and Ce3+/Ce2+). Besides earlier defined luminescence centers comprising Eu2+ ions in orthorhombic and cubic coordination positions of YF3 crystal lattice, the studied phosphors involve two additional types of luminescence centers relating to Eu(II), supposedly corresponding to Eu2+ in the same coordination positions located on the surface of the phosphor particles. Using the obtained data, an energy chart of Eu(II)-based luminescence centers in YF3:Eu nanosized phosphors is suggested. The resulting nanoscale particle size and luminescence spectra features of the synthesized phosphors YF3:Ce and YF3:Eu make them potentially useful for photodynamic therapy of cancer in combination with the photosensitizer Rose Bengal. The composition involving the synthesized Y2O3:Eu phosphor and photosensitizer Photoditazine was shown to provide an effective destruction of tumor cell cultures. Highlights: Y2O3:Eu nanosized phosphor is synthesized via hydrothermal precipitation followed by RTA. Finely dispersed Y2Si2O7:Eu is synthesized via hydrothermal precipitation with the addition of Aerosil followed by microwave annealing. An energy chart of Eu(II)-based luminescence centers in YF3:Eu nanosized phosphors is defined. Nanosized phosphors promising for the application in photodynamic therapy of cancer coupled with the photosensitizer Rose Bengal are obtained. [ABSTRACT FROM AUTHOR]

In this study, NiO films were fabricated through radio frequency sputtering with various oxygen flow rates and processed via rapid thermal annealing under Ar, O2, and N2 atmospheres. The electrical, optical, and crystallographic properties of the NiO films were influenced by their oxygen content in each film. As the oxygen content, carrier concentration, and resistivity increased, transmittance and mobility decreased. The carrier mobility of the NiO film in the p-type layer of the photodetector requires improvement. Rapid thermal annealing (RTA) has been widely used to improve the crystallinity and mobility of films. However, the reduction in oxygen content during RTA causes a decrease in the carrier concentration and transmittance of NiO films. Regarding the aim of preventing a reduction in oxygen content in the NiO films due to the RTA process, an O2 atmosphere (compared with Ar and N2 atmospheres) was identified as the optimal condition for mobility (3.42 cm2/V·s) and transmittance (50%). [ABSTRACT FROM AUTHOR]

The RF-sputtered β-Ga2O3 films prepared on sapphire substrates were treated by rapid thermal annealing (RTA) with an ultrafast processing time of 30 s. The effects of RTA at different process temperatures from 600 to 800 °C on the β-Ga2O3 films were researched. Meanwhile, the schematic diagram for the RTA-induced lattice expansion of films was proposed. The experimental results showed that the variation of Ga oxidation states and lattice oxygen was demonstrated, revealing a greater value of lattice oxygen at 700 °C. The (-201) orientation of Ga2O3 films is observed at 700 °C and 800 °C, where the (111) orientation additionally appeared at 800 °C. The larger grain size and interplanar distance of 4.71 Å for the (−201) orientation were also obtained at 700 °C, accounting for the high-quality β-Ga2O3 films and their lattice expansion. As a result, this RF-sputtered β-Ga2O3 films via the RTA process not only provide a new reference condition but also suitable for optoelectronic devices requiring control of crystallizing temperature and lattice variation.

Buckypaper (BP), a flexible and porous material, exhibits photovoltaic properties when exposed to light. In this study, we employed radio frequency (RF) sputtering of zinc oxide (ZnO) followed by rapid thermal annealing to enhance the photovoltaic response of BP. We investigated the impact of various sputtering parameters, such as the gas flow ratio of argon to oxygen and deposition time, on the morphology, composition, resistivity, and photovoltaic characteristics of ZnO-modified BP. Additionally, the photovoltaic performance of the samples under different illumination modes and wavelengths was compared. It was found that optimal sputtering conditions—argon to oxygen flow ratio of 1:2, deposition time of 20 min, and power of 100 watts—resulted in a ZnO film thickness of approximately 45 nanometers. After annealing at 400 °C for 10 min, the ZnO-modified BP demonstrated a significant increase in photocurrent and photovoltage, along with a reduction in resistivity, compared to unmodified BP. Moreover, under gradient illumination, the ZnO-modified BP exhibited a photovoltage enhancement of 14.70-fold and a photocurrent increase of 13.86-fold, compared to uniform illumination. Under blue light, it showed a higher photovoltaic response than under other colors. The enhancement in photovoltaic response is attributed to the formation of a Schottky junction between ZnO and BP, an increased carrier concentration gradient, and an expanded light absorption spectrum. Our results validate that ZnO sputtering followed by annealing is an effective method for modifying BP for photovoltaic applications such as solar cells and photodetectors.

Effect of rapid thermal annealing conditions on the specific resistance of the ohmic contacts of Ti/Al/Ni/Au metallization with layer thicknesses of 20/120/40/40 nm to the GaN/AlGaN heterostructure with a two-dimensional electron gas on a sapphire substrate has been discovered by transmission line measurement. Rapid thermal annealing of the samples was carried out by the contact heating from the sapphire substrate side in a nitrogen atmosphere at the temperature range from 750 to 1000 °C for 30, 60, and 90 s. It has been discovered that the dependence of the specific contact resistance on the temperature contains two temperature optimums, at which the specific contact resistance of the ohmic contact is less than 1 ⋅ 10–4 Ohm⋅ cm2. The appearance of the first temperature optimum is due to the decrease of the distance from the diffusion front of the low-resistance layer of intermetallic compounds formed during the rapid thermal annealing of the Ti/Al/Ni/Au metallization to the region of the two-dimensional electron gas. Outside the first temperature optimum, an increase in the specific contact resistance of up to 9 ⋅ 10–3 Ohm⋅ cm2 is observed, due to the absorption of the AlGaN layer by a low-resistance layer of intermetallic compounds, which leads to the degradation of the two-dimensional electron gas under the contacts and deterioration of its conductive properties. The second temperature optimum is due to the passage of the diffusion front of the two-dimensional electron gas region and the establishment of a side contact between the low-resistance intermetallic layer and the two-dimensional electron gas, which leads to the decrease in the specific contact resistance. With an increase in the fast thermal annealing time from 30 to 90 s the shift of the interval of the first temperature optimum from 800 to 775 °C for the lower boundary and from 825 to 800 °C for the upper boundary, and for the second temperature optimum from 875 to 850 °C for the lower boundary, and from 950 to 875 °C for the upper boundary is observed, which is due to an equivalent increase in the diffusion depth of the Ti/Al/Ni/Au metallization components. The results obtained can be used in the technology for creating GaN-based products with a two-dimensional electron gas.

The post-processing of CuInGaSe2 (CIGS) thin films deposited using a single-target sputtering method was studied. Post-processing annealing was performed in a traditional muffle furnace and rapid thermal processing (RTP) tube furnace. The samples were annealed at 450°C for 10 min in a muffle furnace and subsequently quenched, whereas multiple quenching cycles were performed in RTP. The structural, optical, elemental, and morphological properties of the samples were analyzed. The obtained XRD data were refined using the Rietveld refinement algorithm, which showed that the c/a value approaches the ideal tetragonal crystal structure in the RTP-treated sample and that the crystallinity of the RTP-treated sample was better than that of the traditional furnace-annealed samples. Optical measurements showed increased absorbance values in the RTP-treated samples compared with the furnace-annealed samples. Bandgap was estimated to be 1.30 eV, 1.22 eV, and 1.18 eV for as-deposited, furnace annealing, and RTP-treated samples. Our experiment showed that better results were obtained in the RTP-treated samples, with a similar parameter used for annealing. [ABSTRACT FROM AUTHOR]

Lead zirconate titanate (PZT) films have shown great potential in piezoelectric micro-electronic-mechanical system (piezo-MEMS) owing to their strong piezoelectric response. However, the fabrication of PZT films on wafer-level suffers with achieving excellent uniformity and properties. Here, we successfully prepared perovskite PZT films with similar epitaxial multilayered structure and crystallographic orientation on 3-inch silicon wafers, by introducing a rapid thermal annealing (RTA) process. Compared to films without RTA treatment, these films exhibit (001) crystallographic orientation at certain composition that expecting morphotropic phase boundary. Furthermore, dielectric, ferroelectric and piezoelectric properties on different positions only fluctuate within 5%. The relatively dielectric constant, loss, remnant polarization and transverse piezoelectric coefficient are 850, 0.1, 38 μC/cm2 and −10 C/m2, respectively. Both uniformity and properties have reached the requirement for the design and fabrication of piezo-MEMS devices. This broadens the design and fabrication criteria for piezo-MEMS, particularly for piezoelectric micromachined ultrasonic transducers. [ABSTRACT FROM AUTHOR]

In this work, we report the influence of annealing time on the electrical properties of Pt thin film resistance-temperature-detectors (RTD) with Ti adhesion layers. It is found that the temperature coefficient of resistance (TCR) of the Pt thin film RTD strongly depends on the air annealing time. Increasing the annealing durations from 1, 3, 10 to 60 min at 900 °C, the TCR tends to rise up firstly, and then drops down. A maximum TCR of 3.2 × 10−3/°C at 25 °C is achieved in the RTD annealed for 3 min, which is larger than most of other reported values. It is believed that the annealing time of 3 min may be sufficient to enlarge the grain size and to reduce the lattice defects, giving rise to the maximum TCR by decreasing the resistance at 25 °C. On the contrary, prolonging the annealing duration causes the interdiffusion and oxidation Ti significantly, which has been clearly evidenced by the depth analyses of X-ray photoelectron spectroscopy. Such interdiffusion and oxidation of Ti reduces the TCR by increasing the resistance. [ABSTRACT FROM AUTHOR]

Improvement in crystallinity was investigated by compensating for stoichiometric deviations of non-selenization processed Cu0.9In0.7Ga0.3Se2 (CIGS) thin films due to highly volatile Se by co-sputtering them with Te followed by rapid thermal annealing. The prepared CIGS:Te thin films did not show any linear correlation between the compositional ratio and the co-sputtering time of Te; however, the deviation parameter (Δs) from the stoichiometry and normalized stoichiometric deviations of Se + Te and In + Ga were largely consistent with the behavior of thin-film properties. The proposed method provides better crystallinity with a large grain size, clear grain boundaries, and low microstrain and dislocation density, resulting in a large volume of the unit cell. The CIGS:Te thin films used as absorbers show improved optical properties compared to the conventional CIGS thin films, with Eg = 1.548 eV. These results can advance the low-cost commercialization of the enhanced-efficiency CIGS:Te thin films without the selenization process. [ABSTRACT FROM AUTHOR]

This study proposed a novel source/drain (S/D) extension scheme to increase the stress in nanosheet (NS) field-effect transistors (NSFETs) and investigated the scheme by using technology-computer-aided-design simulations. In three-dimensional integrated circuits, transistors in the bottom tier were exposed to subsequent processes; therefore, selective annealing, such as laser-spike annealing (LSA), should be applied. However, the application of the LSA process to NSFETs significantly decreased the on-state current (Ion) owing to diffusionless S/D dopants. Furthermore, the barrier height below the inner spacer was not lowered even under on-state bias conditions because ultra-shallow junctions between the NS and S/D were formed far from the gate metal. However, the proposed S/D extension scheme overcame these Ion reduction issues by adding an NS-channel-etching process before S/D formation. A larger S/D volume induced a larger stress in the NS channels; thus, the stress was boosted by over 25%. Additionally, an increase in carrier concentrations in the NS channels improved Ion. Therefore, Ion increased by approximately 21.7% (37.4%) in NFETs (PFETs) compared with NSFETs without the proposed scheme. Additionally, the RC delay was improved by 2.03% (9.27%) in NFETs (PFETs) compared with NSFETs using rapid thermal annealing. Therefore, the S/D extension scheme overcame the Ion reduction issues encountered in LSA and significantly enhanced the AC/DC performance. [ABSTRACT FROM AUTHOR]

We report on the effect of rapid thermal annealing (RTA) on GaAs1−x−Nx layers, grown by molecular beam epitaxy (MBE), using room temperature spectroscopic ellipsometry (SE). A comparative study was carried out on a set of GaAs1−x−Nx as-grown and the RTA samples with small nitrogen content (x = 0.1%, 0.5% and 1.5%). Thanks to the standard critical point model parameterization of the GaAs1−x−Nx extracted dielectric functions, we have determined the RTA effect, and its nitrogen dependence. We have found that RTA affects more samples with high nitrogen content. In addition, RTA is found to decrease the E1 energy nitrogen blueshift and increase the broadening parameters of E1, E1+Δ1, E′0 and E2 critical points.

Effect of rapid thermal annealing temperature on the electrophysical properties of the ohmic contact of Ti/Al/Ni metallization with layer thicknesses of 20/120/40 nm to the GaN/AlGaN heterostructure with a two-dimensional electron gas on a sapphire substrate has been discovered by transmission line measurement and secondary ion mass spectroscopy methods. Rapid thermal annealing of the samples was carried out in a nitrogen atmosphere at the temperature ranging from 850 to 900 °C for 60 s. It has been discovered that a high-resistance heterostructure layer with a thickness of about 25 nm is located on the initial samples between metallization and the two-dimensional electron gas, which prevents the formation of ohmic contact. After rapid thermal annealing at the temperature of less than 862,5 °C, the metallization components interact with each other and with the heterostructure, which leads to the decrease in the thickness of the high-resistance heterostructure layer to 15–20 nm and to the nonlinearity of the I – V characteristic. At rapid thermal annealing temperatures in the range from 862,5 to 875 °C, the thickness of the high-resistance heterostructure layer decreases to several nanometers due to the interaction of Ti/Al/Ni metallization components with the heterostructure, which promotes the tunneling effect of charge carriers and formation of a high-quality ohmic contact with a resistivity of about 1⸱10–4 Ohm∙cm2 . With an increase of the rapid thermal annealing temperature over 875 °C, the interaction of the metallization and heterostructure components occurs throughout the entire depth, the two-dimensional electron gas degrades, and the I – V characteristic of the contact becomes nonlinear. The results obtained can be used in the technology for creating GaN-based products with a two-dimensional electron gas.

The wake‐up phenomenon widely exists in hafnia‐based ferroelectric capacitors, which causes device parameter variation over time. Crystallization at a higher temperature has been reported to be effective in eliminating wake‐up, but high temperature may yield the monoclinic phase or generate more oxygen vacancies. In this work, a unidirectional annealing method is proposed for the crystallization of Hf0.5Zr0.5O2 (HZO) superlattice ferroelectrics, which involves heating from the Pt/ZrO2 interface side. It is demonstrated that 600 °C annealing only leads to a moderate content of monoclinic phase in HZO, and the TiN/HZO/Pt capacitor exhibits wake‐up free nature and a switchable remnant polarization value of 27.4 µC cm−2. On the other hand, heating from the TiN/HfO2 side, or using 500 °C annealing temperature, could yield ferroelectric devices that require a wake‐up process. The special configuration of Pt/ZrO2 is verified by comparative studies with several other superlattice structures and HZO solid‐state solutions. It is discovered that heating from the Pt/HfO2 side at 600 °C leads to high leakage current and a memristor behavior. The mechanisms of ferroelectric phase stabilization and memristor formation have been discussed. The unidirectional heating method can also be useful for other hafnia‐based ferroelectric devices. [ABSTRACT FROM AUTHOR]

Improving the detection limit of surface-enhanced Raman scattering (SERS) is a significant issue for the design and application of plasmon substrate. It always suffers from the weak affinity of probe molecules on the nanoscale surface, uncontrollable aggregation behaviors of nanoparticles, and strong fluorescence of the detected substance. In this paper, AgNPs/SiO2 substrate is prepared by a rapid thermal annealing method with a mean size of 87.9 ± 30.7 nm. A layer of 5–30 nm PVA (polyvinyl alcohol) film is used as the stabilizer of AgNPs. With PVA coating, AgNPs can improve the detection limit of gentian violet by three magnitudes, compared with the one on undecorated AgNPs which is just 10−5 mol/L. In the sensitive detection using coated AgNPs/SiO2 substrate, PVA possibly plays three significant roles, affinity increaser between gentian violet and silver nanoparticles, fluorescence inhibiter of gentian violet, and stabilizer of Ag nanoparticles. The results provide a modification method for improving SERS sensitivity of plasmon substrate, which uses convenient and low-cost rapid thermal annealing as the patterning method and PVA as the coater, an advantageous technology for plasmon substrate application into trace detection. [ABSTRACT FROM AUTHOR]

Microwave annealing with subsequent rapid thermal annealing (MWA+RTA) is proposed for HfZrOx-based germanium (Ge) p-channel ferroelectric FET (p-FeFET) memory to concurrently improve the interfacial quality while obtaining the required polarization, leading to a memory window of 2.5 V by ±4 V operation, good read latency, robust endurance up to 107 cycles for 1 bit/cell operation and each stable state for 3 bits/cell (triple-level cell, TLC) operation up to 105 cycles for the first time. Reversing the annealing sequence (RTA+MWA) degrades the performance and attests to the importance of thermal budget control. The proposed annealing scheme makes the Ge FeFETs, even with planar structure, quite competitive compared to other Si-, SiGe- and Ge-based FeFETs in terms of low-voltage TLC capability with high reliability, enabling high-density embedded memory for future nodes. [ABSTRACT FROM AUTHOR]

• Epi-Si growth on epi-Gd2O3/Si(111) virtual substrate using RF sputtering. • Pole figure and Transmission electron microscopy confirm Si epitaxy. • Lower Si thickness and higher capping deposition time facilitate epitaxial growth. • Wafer-scale epi-Si growth on epi-Gd2O3/Si(111) substrate for SOI Application. Silicon on Insulator (SOI) technology has been the promising solution for the On-chip low-power mixed-signal systems. However, the traditional smart-cut method for SOI wafer fabrication is costly. Hence, in this work, we present an optimized methodology to fabricate a wafer scale single-crystalline Si on epitaxial Gd 2 O 3 /Si(111) substrate (SOXI) using a low-cost, high volume manufacturable (HVM)-friendly Radio Frequency magnetron sputtering technique for SOI application. The grown Si and Gd 2 O 3 layers are physically characterized using high-resolution X-ray Diffraction and high-resolution Transmission Electron Microscopy (HRTEM). The Grazing Incidence X-ray Diffraction, Pole Figure, and HRTEM imaging confirm the formation of an epitaxial Top-Si layer on the epitaxial-Gd 2 O 3 /Si(111) substrate. Hence, we demonstrate a low-cost, HVM-friendly technique for the fabrication of SOXI wafers. [ABSTRACT FROM AUTHOR]

Polycrystalline InAs films were prepared on GaSb substrates using direct current (DC) magnetron sputtering. The effects of different substrate temperatures, sputtering power, annealing methods, and annealing temperatures on the film structure and morphology were studied using XRD, Raman spectroscopy, XPS, UPS, SEM, EDS, and HRTEM. The results confirmed the formation of polycrystalline InAs films with a (111) crystal orientation on GaSb substrates. It was found that excessively high substrate temperatures lead to Sb diffusion, and high sputtering power introduces defects, which deteriorate the crystallinity of InAs films. InAs films with good crystallinity were achieved at a substrate temperature of 450 °C and a sputtering power of 90 W. Comparing the annealing methods, rapid thermal annealing (RTA) effectively suppresses the diffusion of Sb. XPS and EDS analyses indicated that annealing causes significant diffusion of Ga and Sb from the GaSb substrate, leading to the formation of oxides such as InSb, SbO 2 , In 2 O 3 , and As 2 O 3. The decomposition of the oxide layer on the substrate surface at 600 °C exacerbates the oxidation of the film. • Polycrystalline InAs films were prepared on GaSb substrates using magnetron sputtering. • Substrate temperature and sputtering power influence the crystallinity of InAs films. • High temperatures (>600 °C) decompose surface oxides on the substrate, exacerbating film oxidation. • The diffusion of Sb and Ga was confirmed, resulting in the formation of InSb and SbO 2. [ABSTRACT FROM AUTHOR]

In this study, few-layer graphene was directly fabricated on a SiO 2 /Si substrate through the rapid thermal annealing of Ni films with low carbon content (C:Ni) deposited by reactivedirect current magnetron sputtering (DCMS). XPS, XRD and TEM results confirmed that carbon atoms were doped into the Ni lattice and there are no carbon clusters embedded in the films. The study investigated various parameters and factors affecting graphene preparation, including the carbon content in the Ni film, the thickness of the Ni film, the annealing temperature, the heating rate, and other relevant factors. Raman spectroscopy revealed that few-layer graphene occurs on the surface of the C:Ni film, with I 2D / I G ratio greater than 1 and I D / I G less than 0.2, indicating the excellent quality of the graphene. Raman mapping images confirmed that the monolayer graphene covered approximately 90 % of the 10 × 10 μm2 area on the surface. Furthermore, it was observed that the low carbon content of the Ni film facilitated the preparation of few-layer graphene. High temperatures were found to enhance carbon diffusion, which has a great impact on the layer number and quality of graphene. The synthesis of graphene can be attributed to metal-induced crystallization and carbon diffusion mechanisms. The experimental findings are expected to greatly advance the synthesis of graphene and broaden its potential applications in various fields. Monolayer graphene can be prepared directly on SiO 2 /Si substrates by annealing nickel films with low carbon content. The number of graphene layers is determined by the carbon content in the nickel film and the preparation parameters. [Display omitted] [ABSTRACT FROM AUTHOR]

Charge-trap based resistive switching (RS) has attracted attention in the resistive random-access memory (RRAM) industry due to its gradual RS behavior for multi-level and synaptic applications. In this work, in order to lower the operating current level closely related to device’s degradation, we applied a hydrogen passivation to Zr3N2 based RRAM devices and investigated the correlation between current level and trap density, such as an interface trap density ( $\text{N}_{\mathrm {it}}$ ) at the Zr $_{3}\text{N}_{2}/p$ -Si layer and nitride trap density ( $\text{N}_{\mathrm {nt}}$ ) within Zr3N2 films, for memory cells annealed in conventional N2 gas as well as H2 gas. Compared to the N2-annealed sample, after H2 annealing, $\text{N}_{\mathrm {it}}$ is lowered by the hydrogen passivation effect, which results in a reduction of both current level at high resistive state (HRS) and variation of HRS and low resistive state (LRS). As a result, in the H2 annealed Zr3N2 RRAM cell, we observed a lower operation voltage/current, longer endurance, and larger read margin due to the hydrogen passivation effect.

Abstract The wake‐up phenomenon widely exists in hafnia‐based ferroelectric capacitors, which causes device parameter variation over time. Crystallization at a higher temperature has been reported to be effective in eliminating wake‐up, but high temperature may yield the monoclinic phase or generate more oxygen vacancies. In this work, a unidirectional annealing method is proposed for the crystallization of Hf0.5Zr0.5O2 (HZO) superlattice ferroelectrics, which involves heating from the Pt/ZrO2 interface side. It is demonstrated that 600 °C annealing only leads to a moderate content of monoclinic phase in HZO, and the TiN/HZO/Pt capacitor exhibits wake‐up free nature and a switchable remnant polarization value of 27.4 µC cm−2. On the other hand, heating from the TiN/HfO2 side, or using 500 °C annealing temperature, could yield ferroelectric devices that require a wake‐up process. The special configuration of Pt/ZrO2 is verified by comparative studies with several other superlattice structures and HZO solid‐state solutions. It is discovered that heating from the Pt/HfO2 side at 600 °C leads to high leakage current and a memristor behavior. The mechanisms of ferroelectric phase stabilization and memristor formation have been discussed. The unidirectional heating method can also be useful for other hafnia‐based ferroelectric devices.

This work investigated the (0002) textured ZnO films without and with the addition of an Au continuous top layer and its effects on their surface wettability and plasmonic resonance characteristics. The ZnO films were directly fabricated onto glass substrates at the synthesized temperature of 300 °C via a plasma-enhanced chemical vapor deposition (PECVD) system, and the as-synthesized ZnO film exhibited an average optical transmittance value of 85%. The ultraviolet (UV) light irradiation can be applied to enhance the hydrophilicity, changing it from a hydrophobic status to hydrophilic status due to the existing and adjustable characteristics of the photocatalytic activity. On the other hand, the surface wetting/contact angle (CA) value of the ZnO film with a controllable surface wettability switched from 94° (hydrophobicity) to 44° (hydrophilicity), after it was exposed to UV light irradiation for 5 min, and stably reversed back to hydrophobicity (92°) via a post-annealed treatment using rapid thermal annealing (RTA) at 350 °C for 5 min in air. A fast, simple, and reversible method for switching between hydrophilic and hydrophobic status is claimed in this present work. The improved surface plasmonic resonance is owning to the coupled electron and photon oscillations that can be obtained and produced at the interface between the flat Au layer and ZnO (metal/metallic oxide) heterostructured films for future applications of various wide-bandgap compound semiconductors. [ABSTRACT FROM AUTHOR]

An investigation was conducted with regard to the effect of etching process on the ferroelectric (FE) characteristics of different device structures with Al-doped HfO2 thin films; further, the effect of the rapid thermal annealing temperature on the FE properties was elucidated using metal-ferroelectric-metal (MFM) capacitors using TiN electrodes with varying thickness and 4 at.% Al-doped HfO2 FE layer. The capacitors were annealed at different temperatures after lithography and etching process; this was aimed at incorporating the FE-orthorhombic phase. The samples annealed after patterning were able to obtain improved FE characteristics due to the amount of tensile stress. The MFM devices that were initially patterned were also studied as a reference. We found that even though it required higher temperature and shorter time to introduce the FE phase, it exhibited more stable as well as promising FE properties and electrical performances with a relatively large remnant polarization (2 P r ∼ 60 ÎĽ C cmâˆ'2), a coercive electric field of approximately 2 MV cmâˆ'1 and high switching current density with less leakage. Our results indicate how the FE properties of the HfO2-based thin films can be engineered through suitable process sequence and post-annealing conditions, thereby verifying the applicable flexibility of FE-HfO2 for semiconductor device integration. [ABSTRACT FROM AUTHOR]

Block copolymer (BCP) self‐assembly‐assisted doping for semiconductors is used to achieve discrete doping with nanometer‐scale junction depth, high throughput, and large area coverage. As devices become smaller and more sophisticated, spatial control of dopants becomes more critical. A variety of doping methods, such as monolayer doping and δ‐doping, have been developed to replace the conventional doping method, ion‐implantation; however, lateral patterning of dopants relies on photo‐ or e‐beam lithography. To address these challenges, a self‐assembling dopant (boron)‐containing BCP is designed to directly pattern dopants on the nanometer scale. This method skips the lithography step and is compatible with directed self‐assembly approaches. The effect of the boron concentration in the BCP on the doping performance is systematically studied by changing the volume fraction of the boron‐containing block while keeping the domain spacing and the mesoscale morphology constant. Successful self‐assembly of the BCP into a hexagonally packed cylindrical morphology is confirmed by small‐angle X‐ray scattering and resonant soft X‐ray scattering with a 26 nm cylinder‐to‐cylinder distance. Doping silicon using these BCPs enables discrete doped areas with shallow (7–13 nm) junction depth as demonstrated by the depth profile of boron, and supported by a sheet resistance study. [ABSTRACT FROM AUTHOR]

The vast high entropy alloy (HEA) composition space is promising for discovery of new material phases with unique properties. This study explores the potential to achieve rare-earth-free high magnetic anisotropy materials in single-phase HEA thin films. Thin films of FeCoNiMnCu sputtered on thermally oxidized Si/SiO 2 substrates at room temperature are magnetically soft, with a coercivity on the order of 10 Oe. After post-deposition rapid thermal annealing (RTA), the films exhibit a single face-centered-cubic phase, with an almost 40-fold increase in coercivity. Inclusion of 50 at.% Pt in the film leads to ordering of a single L1 0 high entropy intermetallic phase after RTA, along with high magnetic anisotropy and 3 orders of magnitude coercivity increase. These results demonstrate a promising HEA approach to achieve high magnetic anisotropy materials using RTA., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Cadmium telluride (CdTe) detectors are usually subjected to elevated temperatures during postprocessing and bonding them to readout electronics while fabricating imaging arrays. We studied the effects of low-temperature and short duration rapid thermal annealing of CdTe bulk as well as CdTe epitaxial-layer-based detectors with evaporated gold contacts. The detectors were annealed in the temperature range of 100 °C–300 °C, and its effect on the detector dark current, gamma detection property, and response stability was studied. For the bulk-detectors, the detector dark current decreased and gamma detection properties as well as the performance stability improved after annealing. However, such improvements were moderate for epitaxial-layer-based detectors. The study of the metal–semiconductor interface of annealed detectors revealed that diffused gold, elemental oxygen, and tellurium oxide existed and extended deep inside the bulk portion in epitaxial detectors; however, they were confined in the surface regions only in bulk-detectors, which likely be the causes of observed results in these two types of detectors. [ABSTRACT FROM AUTHOR]

One drawback of self-organized quantum dots is their low optical gain. The development of new shaping methods that would allow higher gain, for example, due to a higher surface density of the QD array, remains an important task to date. In the present work, arrays of quantum dots have been formed by substituting phosphorous atoms with arsenic ones in a thin InGaP epilayer. Based on transmission electron microscopy data, the surface density was estimated to be about 1.3 × 1012 cm−2, which is one of the highest values for quantum dots on GaAs. The influence of an additional InGaAs epilayer (quantum well) on the luminescence properties of quantum dots was investigated in a wide temperature range and different optical pumping levels. It was found that placing the quantum well under the layer of quantum dots has little effect on the central emission wavelength, while quantum dots covered with the InGaAs demonstrate a strong red shift of the luminescence spectrum. A transition from a nonequilibrium to an equilibrium distribution of charge carriers over quantum-dot states, related to the lateral transport of charge carriers over quantum dot array, similar to that previously observed in In(Ga)As Stranski-Krastanow quantum dots, was revealed. This is manifested in a change in temperature dependencies of the linewidth and peak position of the photoluminescence band. For the structures under study, this transition occurs at a temperature of about 125 K. Rapid thermal annealing of the structures allows to increase the integrated photoluminescence intensity of quantum dots up to 4 times, while the maximum of the spectrum remains almost unchanged, provided that the annealing temperature does not exceed 620 °C. [ABSTRACT FROM AUTHOR]

A major challenge in transistor technology scaling is the formation of controlled ultrashallow junctions with nanometer-scale thickness and high spatial uniformity. Monolayer doping (MLD) is an efficient method to form such nanoscale junctions, where the self-limiting nature of semiconductor surfaces is utilized to form adsorbed monolayers of dopant-containing molecules followed by rapid thermal annealing (RTA) to diffuse the dopants to a desired depth. Unlike ion implantation, the process does not induce crystal damage, thus making it highly attractive for nanoscale transistor processing. To date, reported MLD processes have relied on solution processing for monolayer formation. Gas-phase processing, however, benefits from higher intra- and interwafer uniformity and conformal coverage of 3D structures and is more desirable for manufacturing. In this regard, we report a new approach for MLD in silicon and germanium using gas-phase monolayer formation. We call this technology gas-phase monolayer doping (GP-MLD). This method relies on sequential pulse-purge cycles of gas-phase dopant-containing molecules to form a boron- or phosphorus-containing monolayer on a target semiconductor surface. Here, we show the feasibility of our approach through the formation of ultrashallow B- and P-doped junctions on Si and Ge surfaces. The mechanism of adsorption is characterized using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Sub-5 nm junction depths with high dopant dose are obtained as characterized by secondary ion mass spectrometry and sheet resistance measurements. Additionally, we demonstrate that area selectivity can be achieved via lithographic patterning of the monolayer dopants before the diffusion step. The results demonstrate the versatility of the GP-MLD approach for formation of controlled and ultrashallow junctions.

In this work, the effect of rapid thermal annealing (RTA) temperature on the ferroelectric polarization in zirconium-doped hafnium oxide (HZO) was studied. To maximize remnant polarization (2Pr), in-plane tensile stress was induced by tungsten electrodes under optimal RTA temperatures. We observed an increase in 2Pr with RTA temperature, likely due to an increased proportion of the polar ferroelectric phase in HZO. The HZO capacitors annealed at 400°C did not exhibit any ferroelectric behavior, whereas the HZO capacitors annealed at 800°C became highly leaky and shorted for voltages above 1 V. On the other hand, annealing at 700 °C produced HZO capacitors with a record-high 2Pr of ∼ 64 μC cm−2 at a relatively high frequency of 111 kHz. These ferroelectric capacitors have also demonstrated impressive endurance and retention characteristics, which will greatly benefit neuromorphic computing applications.