Rapid Thermal Annealing Research Articles

Structural and optical properties of Cu implanted Ge thin films

Effects of rapid thermal annealing (RTA) on 100 keV Cu implanted germanium (Ge) thin films were studied in the present report. The Cu ion implantation into Ge films was carried out at different ion fluences 5 × 1015 and 1 × 1016 ions/cm2. Subsequently, the implanted samples were subjected to RTA at 600 °C. XRD and Raman results illustrate the amorphization of implanted films, whereas RTA results in crystallization. Crystallite size increases from 10.5 to 11.6 nm with fluence for RTA-treated samples. The bandgap of pristine film is 0.73 eV, which gets narrowed to 0.59 eV with an increase in ion fluence. RTA leads to increase in band gap up to 1.16 eV due to recovery of lattice damage and recrystallization of films. XPS analysis of RTA-treated implanted films reveals the presence of Ge, Ge suboxides, and Cu. The broad PL emission in the visible region signifies the possible use of Ge for optoelectronic applications.

Sol-gel synthesis and multiferroic properties of pyrochlore-free Pb(Fe0.5Nb0.5)O3 thin films

Lead iron niobate (PbFe0.5Nb0.5O3 – PFN) thin films were synthesized by a modified sol-gel route, which offers the advantage of a rapid, simple and non-toxic reaction method. Polycrystalline perovskite-structured PFN thin films without pyrochlore phases were obtained on Pt/Ti/SiO2/Si substrates after sintering by rapid thermal annealing at 650 °C. TEM and AFM images confirmed the excellent quality of the sintered film, while EDS spectroscopy revealed the presence of oxygen vacancies near the film/substrate interface. Electric measurements show good dielectric properties and ferroelectric behavior, characterized by typical C–V curves and well-defined P-E ferroelectric loops at 1 kHz, with remanent polarization values of ∼12 μC/cm2. The polarization, however, increases with decreasing frequency, indicating the presence of leakage currents. I–V measurements show a significant increase in DC-conduction at relatively low fields (around 100 kV/cm). The films display ferromagnetic behavior at room temperature, with magnetic remanence around 30 emu/cm3 and a coercive field of 1 kOe. These values are significantly higher than those obtained for PFN powders fabricated by the same sol-gel route, as well as the magnetization values reported in the literature for epitaxial films.

Research On Mg Doping in Nitride Semiconductor Materials

Summarized the achievements of various model research directions in nitride Mg doped semiconductors in this thesis. Due to the Internal properties of Mg acceptors which resulting the low ionization rate of acceptor, and the low hole mobility in heavily Mg doped nitrides, the conductivity of Mg doped nitrides is limited. At present, research is divided into three categories of models, one is a new type of polarization model. This model adopts a built-in electron polarization ionization acceptor dopant in the bulk uniaxial semiconductor crystal, and provides an attractive solution for the problem of P-type and n-type doping in broadband gap semiconductors. The other two are the traditional thermal activation model. There are mainly ultra-high-pressure-annealing (UHPA) and multicycle rapid thermal annealing (MRTA) respectively. Both of these schemes can activate more Mg impurities, resulting in higher conductivity in nitrides. The principles, advantages and disadvantages, and future development prospects will be explained of these three models in this thesis.

Wetting state and mechanical property alteration for the Fe3Si films using rapid thermal annealing under various temperatures

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.

Effect of rapid thermal annealing on the charge storage kinetics of conductive N-doped SnO2 thin film anodes for Li-ion batteries

This study focuses on the fabrication of a flexible thin film electrode composed of N-doped tin oxide (SnO2: N). The fabrication process involves sputtering SnO2 onto a Cu foil sheet using radio frequency (RF) magnetron sputtering, conducted under an N2 atmosphere. The deposited thin films are subsequently exposed to annealing treatment using rapid thermal annealing (RTA) at temperatures ranging from 200 to 400 °C. The primary objective of this study is to get an understanding of the effects of N-doping, annealing temperature on the growth of SnO2: N. as well as the influence of film thickness on the crystallographic state. We evaluate their thin-film anode performance for lithium-ion batteries (LIBs). The specific capacity of the as-deposited SnO2 thin films standing at 859 mAh g−1 when measured at 1 mA g−1. This enhanced capacity is attributed to the limited crystal growth in ultrathin SnO2, a factor that effectively combats electrode degradation while simultaneously improving the lithium-ion diffusion coefficient and electron kinetics of the electrode. However, the SnO2: N film that undergoes annealing at 400 °C demonstrates remarkable cyclic retention, reaching 82 %. This improvement is due to the enhanced electrical conductivity resulting from annealing, which prevents the aggregation of tin (Sn) and effectively accommodates the volume changes that occur in prolonged cycles. Additionally, this synchronized approach involving sputtering and RTA is proving to be a simple, efficient, and scalable method. It holds the potential to emerge as a valuable strategy to produce anode materials for lithium-ion batteries.

Complementary use of atom probe tomography (APT) and differential hall effect metrology (DHEM) for activation loss in phosphorus-implanted polycrystalline silicon

The objectives of this study are to explore the activation ratios of implanted phosphorus dopants in polycrystalline silicon (poly-Si), and to reveal the role of grain boundary segregation in incomplete activation using atom probe tomography (APT) and differential Hall effect metrology (DHEM). After implantation and rapid thermal annealing, the results of APT revealed pronounced segregation toward grain boundaries that provides rapid diffusion paths for phosphorus. Peak concentrations of phosphorus segregations in the grain boundaries of the regrown and non-regrown regions were measured to be 4.38E21 and 2.17E21 atoms/cm³ that correspond to activation ratios of 6 % and 1 %, respectively. In contrast, phosphorus concentrations within grain interiors were found to be 6.86E20 and 1.72E19 atoms/cm³, corresponding to activation ratios of 39 % and nearly 100 % in the regrown and non-regrown regions, respectively. This research highlights a novel approach for evaluating site-specific activation ratios in poly-Si through the integrated use of DHEM and APT.

Phase-controlled molybdenum dioxide electrodes by RF reactive magnetron sputtering for achieving high-k rutile TiO2 dielectric

Molybdenum dioxide (MoO2) has recently garnered attention as a promising oxide electrode for next-generation dynamic random-access memory capacitors owing to its high work function, low resistivity, and good thermal stability. The formation of pure, reliable MoO2 films is a significant challenge because of their higher formation energy than that of non-conductive orthorhombic molybdenum trioxide (MoO3). Herein, we investigated the controlled growth of MoO2 films by manipulating the process pressure and oxygen-to-argon (O2/Ar) ratio using radio frequency reactive magnetron sputtering. By increasing the O2/Ar ratio at a fixed process pressure (pp), sputtered MoOx films were fabricated as metallic Mo, monoclinic MoO2, and orthorhombic MoO3. The MoO2 film with Mo/O atomic ratio of 0.5 was achieved in the narrow process window of O2/Ar ratio of 0.22 and pp = 3 mtorr. The MoO2 films exhibited a smooth surface morphology with a root mean square roughness of 0.34–0.68 nm. The resistivity of MoO2 film was 972 μΩ cm, which was decreased to 374–524 μΩ cm by rapid thermal annealing in N2 at 600 °C-800 °C. The phase-controlled MoO2 electrode led to the in-situ crystallization of high-k rutile TiO2 with a dielectric constant of 93 via local epitaxial growth. This might be attributed to the excellent coherence in the atomic arrangement and low lattice mismatch between the distorted rutile MoO2 (011) and rutile TiO2 (110) planes.

Effect of rapid thermal annealing treatment on up-conversion luminescence in Er3+/Yb3+ co-doped NaYF4 oxy-fluoride glass-ceramics

The heat-treatment plays a decisive role in the process of crystal phase precipitation and the microscopic features of the fluoride particles, which determines the optical transmittance and up-conversion luminescence (UCL) properties. In this work, we successfully synthesized Er3+/Yb3+ co-doped UCL transparent oxy-fluoride glass-ceramics (GCs) by precipitation of NaYF4 nanoparticles using a rapid thermal annealing (RTA) treatment with ultra-high heating rate (100 K/s). The particle sizes of NaYF4 nanoprecipitation inside glass-ceramic is only 4–5 nm, which is much smaller than the 40–50 nm particle sizes obtained using normal-heating treatment. The GCs with ultra-small particle sizes provided a very high optical transmittance that is close to that of all-amorphous glass, but the intensity of UCL was similar to that of a sample prepared using a slower heating rate. Finally, under different heat treatment conditions the Er3+/Yb3+ co-doped NaYF4 transparent GCs with different particle sizes can be produced, the color and intensity of UCL were controllable.

SOS pseudo-FeFETs after furnace or rapid annealings and thining by thermal oxidation

The silicon-on-sapphire (SOS) pseudo-MOSFETs with high-k buried hafnium dioxide interlayer (IL) were investigated after the hydrogen induced Si and HfO2 layer transfer on c-sapphire wafers and annealing at 600–1100 °C. HRTEM, GIXRD and Raman measurements were used to reveal the hafnia phases for furnace and rapid thermal annealings (FA and RTA).

Enhanced temperature coefficient of resistance of VOX-based uncooled microbolometers manufactured by plasma enhanced atomic layer deposition

Vanadium oxide (VOX) is a promising material for developing the sensor film of uncooled microbolometers. However, amorphous VOX film, which is typically formed on the Si substrate, is unstable due to ambient unwanted oxidation in air, making their resistance too high to be employed in microbolometers. Therefore, studies on improving the quality and stability of VOx film are still ongoing. This study presents our strategies based on plasma-enhanced atomic layer deposition (PEALD) and rapid thermal annealing (RTA) for manufacturing VOx films with high crystallization and stability. The VOx sensing layer for microbolometers was fabricated at a low process temperature of 370 °C using NH3 gas, and the rapid thermal anneal was performed as the essential post-deposition annealing process for improving the VOx crystallization. Besides, in-situ deposition of an Al2O3 layer on the VOx film improves its stability. Compared with a bare VOx film, our developed Al2O3/VOx film shows an improvement of −3.5%/K in the temperature range of 298–328 K. For the optimized sample, changes in the electrical, chemical, and surface characteristics of the VOx film due to Al2O3 or Al-doping are studied and discussed in detail to find the mechanism of that improvement.

Low thermal budget V/Al/Mo/Au ohmic contacts for improved performance of AlGaN/GaN MIS-HEMTs

We report on the highly improved performance of Al2O3/AlGaN/GaN MIS-HEMTs using a V/Al/Mo/Au metal stack as ohmic electrodes. Transfer length method test structures using a V/Al/Mo/Au metal stack annealed at a temperature of 660 °C revealed highly linear current–voltage curves and smooth surface morphology. Compared with reference MIS-HEMTs using Ti/Al/Mo/Au annealed at the standard rapid thermal annealing temperature of 880 °C, V-based devices exhibited less hysteresis of transfer curves and showed higher gate controllability of the drain current, suggesting a highly improved Al2O3/AlGaN interface. Measurements and analyses of capacitance–voltage characteristics of corresponding MIS-capacitors corroborated these findings. The V-based ohmic contact could open new avenues towards enhanced GaN-based MIS-HEMTs performance.

Fabrication of Porous Heteroatom‐Doped Carbon Networks via Polymer‐Assisted Rapid Thermal Annealing

AbstractPorous 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 ( ≈ 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.

P-type conductive Ga2O3 epilayers grown on sapphire substrate by phosphorus-ion implantation technology

This study utilized various phosphorus-ion implantation techniques, incorporating low, medium, and high doses, to investigate the electrical properties of unintentionally doped β-Ga2O3 epilayers. These epilayers were grown on sapphire substrates by metalorganic chemical vapor deposition.Specifically, the low-dose implantation involved phosphorus ions at concentrations of 1.6✕1013, 1✕1012 and 2.5✕1012 atoms/cm2, administered at implantation energies of 100, 50, and 40 keV, respectively. The medium-dose implantation utilized phosphorus ions at concentrations of 1.6✕1014, 1✕1013 and 2.5✕1013 atoms/cm2, at the same implantation energies. Finally, the high-dose implantation employed phosphorus ions at concentrations of 1.6✕1015, 1✕1014 and 2.5✕1014 atoms/cm2, with implantation energies of 100, 50, and 40 keV, respectively. The implantation parameters were also simulated using the Stopping and Range of Ions in Matter software, while the actual concentration of phosphorus ions was measured via secondary ion mass spectrometry. Subsequently, Ni and Au were deposited on the annealed phosphorus-implanted β-Ga2O3 epilayers, followed by rapid thermal annealing at 600 °C in a nitrogen environment for 1 min, for Hall measurement. The electrical properties of the phosphorus-implanted β-Ga2O3 epilayers were assessed through Hall measurements. Notably, the β-Ga2O3 epilayers implanted with middle and high doses displayed p-type behavior. The resistivity of the p-type β-Ga2O3 epilayers with middle and high doses measured 9.699 and 6.439 Ω cm, respectively, as determined by Hall measurements. Additionally, the hole carrier concentrations for these doses were measured as 1.612 × 1018 and 6.428 × 1017, respectively. Consequently, the phosphorus ion implantations using middle and high doses were proven effective in obtaining p-type Ga2O3. To further explore the defect formation energies and Fermi energies of substitutional phosphorus defects within the β-Ga2O3 lattices, first-principles density-functional simulations were employed.

Nanoscale effect on the formation of the amorphous Ni silicide by rapid thermal annealing from crystalline and pre-amorphized silicon

The Ni monosilicide alloyed with Pt is widely used as contact material in advanced microelectronics devices and a good knowledge of silicide formation kinetics is required for the process control. In this work, the nature, and the growth kinetics of the first silicide obtained during the solid-state reaction between the Ni0.9Pt0.1 and the Si are studied for different pre amorphization implant (PAI) conditions as well as for a reference sample without PAI. Reactions between a 10 nm thick Ni0.9Pt0.1 film and Si (100) substrate are analyzed after several rapid thermal anneals (RTA). The nature of the first silicide is determined by Fourier Transform of TEM images and by chemical TEM-EDX analyses. The silicide growth behavior is determined by measuring the silicide thickness by X ray reflectivity (XRR) after the partial reaction induced by RTAs at different temperatures and times. To determine the growth law, the linear parabolic model is first considered but a nonlinear reactive diffusion model must be developed to accurately reproduce the experimental results. From this model, the effective diffusion coefficient as well as its activation energy were determined for the three samples with PAI and the reference sample without PAI. The influence of the driving force on the nonlinear diffusion for thin films is proved, and the impact of the amorphous substrate on the kinetics parameters is quantified and compared to the literature.

Innovative process to obtain thin films and micro-nanostructured ZrN films from a photo-structurable ZrO2 sol-gel using rapid thermal nitridation

Zirconium nitride (ZrN) is widely used in many industrial sectors for its outstanding performances including its mechanical properties, high chemical and thermal stability. Associated with its plasmonic behavior, these properties make ZrN a suitable candidate for optical applications at high temperature or in extreme environments. The authors present an innovative, easy-to-use and rapid process for producing ZrN thin films from a photo-structurable ZrO2 sol-gel using a rapid thermal nitridation (RTN) process. In this process, a ZrO2 sol-gel layer is converted into a ZrN thin film in a few minutes by rapid thermal annealing (RTA) under ammonia gas. Compared to physical or chemical vapor deposition, usually used to produce ZrN thin films, the advantages of the sol-gel method include suitability for non-planar and large substrates and the possibility of nanotexturing of crystallized ZrN surfaces in considerably less time, at a larger scale and at a lower cost. The ZrO2 and ZrN thin films were characterized by Raman spectroscopy, X-ray diffraction and Transmission Electron Microscopy, to confirm complete nitridation. The optical, electrical and tribological properties were also investigated. Finally, the nitridation method was also used on structured ZrO2 layers and showed the versatility of the process e.g. enabling the production of micro-nanostructured ZrN films without using any etching techniques.

Mid-wave infrared photoluminescence from low-temperature-grown PbSe epitaxial films on GaAs after rapid thermal annealing

We investigate the beneficial effects of rapid thermal annealing on structure and photoluminescence of PbSe thin films on GaAs (001) grown below 150 °C, with a goal of low temperature integration for infrared optoelectronics. Thin films of PbSe deposited on GaAs by molecular beam epitaxy are epitaxial at these reduced growth temperatures, yet the films are highly defective with a mosaic grain structure with low angle and dendritic boundaries following coalescence. Remarkably, we find that rapid thermal annealing for as short as 180 s at temperatures between 300 and 425 °C in nitrogen ambient leads to extensive re-crystallization and transformation of these grain boundaries. The annealing at the same time dramatically improves the band edge luminescence at 3.7 μm from previously undetectable levels to nearly half as intense as our best conventionally grown PbSe films at 300 °C. We show using an analysis of laser pump-power dependent photoluminescence measurements that this dramatic improvement in the photoluminescence intensity is due to a reduction in the trap-assisted recombination. However, we find it much less correlated with improved structural parameters determined by x-ray diffraction rocking curves, thereby pointing to the importance of eliminating point defects over extended defects. Overall, the success of rapid thermal annealing in improving the luminescent properties of low growth temperature PbSe is a step toward the integration of PbSe infrared optoelectronics in low thermal budget, back end of line compatible fabrication processes.

Reduced thermal resistance of amorphous Al2O3 thin films on β-Ga2O3 and amorphous SiO2 substrates via rapid thermal annealing

The impact of rapid thermal annealing (1000 °C for 1 min) on the thermal transport properties of amorphous alumina (a-Al2O3) thin films grown by atomic layer deposition on β−Ga2O3 and amorphous silica (a-SiO2) substrates is determined using frequency-domain thermoreflectance measurements. The annealing more than doubles the a-Al2O3 thermal conductivity for both substrates (1.54 ± 0.13 to 3.14 ± 0.27 W m−1 K−1 for β−Ga2O3 and 1.60 ± 0.14 to 3.87 ± 0.33 W m−1 K−1 for a-SiO2) while keeping the film amorphous. The thermal conductivity increase is attributed to partial recrystallization and off-gassing of embedded impurities. Annealing halves the thermal boundary resistance of the a-Al2O3/a-SiO2 interface (10.5 ± 1.0 to 4.47 ± 0.42 m2 K GW−1), which is attributed to compositional mixing and structural reorganization that are enabled by the elastic matching of these two materials. The thermal boundary resistance of the a-Al2O3/β−Ga2O3 interface is not affected by annealing due to the elastic mismatch. Reducing the thermal resistance of a-Al2O3 dielectric films and adjacent interfaces by annealing will promote lateral heat spreading adjacent to hot spots and improve device longevity.

Carbon Nanowalls as Anode Materials with Improved Performance Using Carbon Nanofibers.

In this paper, a new synthesis of carbon nanofibers (CNFs)/carbon nanowalls (CNWs) was performed to improve the characteristics of anode materials of lithium-ion batteries by using the advantages offered by CNWs and CNFs. Among the carbon-based nanomaterials, CNWs provide low resistance and high specific surface area. CNFs have the advantage of being stretchable and durable. The CNWs were grown using a microwave plasma-enhanced chemical vapor deposition (PECVD) system with a mixture of methane (CH4) and hydrogen (H2) gases. Polyacrylonitrile (PAN) and N,N-Dimethyl Formamide (DMF) were stirred to prepare a solution and then nanofibers were fabricated using an electrospinning method. Heat treatment in air was then performed using a hot plate for stabilization. In addition, heat treatment was performed at 800 °C for 2 h using rapid thermal annealing (RTA) to produce CNFs. A field emission scanning electron microscope (FE-SEM) was used to confirm surface and cross-sectional images of the CNFs/CNWs anode materials. Raman spectroscopy was used to examine structural characteristics and defects. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and constant current charge/discharge tests were performed to analyze the electrical characteristics. The synthesized CNFs/CNWs anode material had a CV value in which oxidation and reduction reactions were easily performed, and a low Rct value of 93 Ω was confirmed.

Tensile stress regulated microstructures and ferroelectric properties of Hf0.5Zr0.5O2 films

The discovery of ferroelectricity in HfO2 based materials reactivated the research on ferroelectric memory. However, the complete mechanism underlying its ferroelectricity remains to be fully elucidated. In this study, we conducted a systematic study on the microstructures and ferroelectric properties of Hf0.5Zr0.5O2 (HZO) thin films with various annealing rates in the rapid thermal annealing. It was observed that the HZO thin films with higher annealing rates demonstrate smaller grain size, reduced surface roughness and a higher portion of orthorhombic phase. Moreover, these films exhibited enhanced polarization values and better fatigue cycles compared to those treated with lower annealing rates. The grazing incidence x-ray diffraction measurements revealed the existence of tension stress in the HZO thin films, which was weakened with decreasing annealing rate. Our findings revealed that this internal stress, along with the stress originating from the top/bottom electrode, plays a crucial role in modulating the microstructure and ferroelectric properties of the HZO thin films. By carefully controlling the annealing rate, we could effectively regulate the tension stress within HZO thin films, thus achieving precise control over their ferroelectric properties. This work established a valuable pathway for tailoring the performance of HZO thin films for various applications.

Relationship between oxidation, stresses, morphology, local resistivity, and optical properties of TiO2, Gd2O3, Er2O3, SiO2 thin films on SiC

The relationship between internal mechanical stresses, surface morphology, nanoscale electrical properties, and optical characteristics in TiO2, Gd2O3, Er2O3, and SiO2 thin films on SiC substrates was investigated. The oxide films were synthesized using the rapid thermal annealing and analyzed through scanning spreading resistance microscopy, photoluminescence, and absorption spectroscopy. Tensile stresses were found in the films, they are attributed to thermal and lattice mismatch, oxidation, and grain boundaries. These stresses influence on surface morphology, resistivity variations, and photoluminescence intensity. Surface roughness and grain structure were found to correlate with variations in resistivity, which were attributed to conductive pathways along grain boundaries and possible metallic phases. Photoluminescence intensity was also observed to correlate with estimated lattice mismatch strain. Gd2O3/SiC exhibited the fewest defects, while Er2O3 and TiO2 showed more, with Er2O3 being the most mismatched and roughest. The results indicate that internal strains in oxide thin films on SiC substrates can influence on surface morphology, leading to formation of defects and spatial inhomogeneity. These fluctuations in local conductivity and luminescence center density have significant implications for dielectric and optical applications. The study provides insights for future processing refinements to mitigate internal strains and enhance the performance of oxide thin films in semiconductor and optical technologies.