Rapid Thermal Annealing Temperature Research Articles

Monitoring of rapid thermal anneal with secondary ion mass spectrometry

Accurate monitoring and, thus, control of rapid thermal anneal (RTA) are critical for manufacturing semiconductor devices. In this work, we developed a method by using secondary ion mass spectrometry (SIMS) aimed to improve long-term repeatability in monitoring RTA. We used a test wafer in a batch implant as SIMS reference for the remaining wafers in the same batch and eliminated the impact from wafer aging and test wafer variation from lot to lot as often encountered in sheet resistance monitoring. In addition, the use of the normalized peak concentration of boron as measured by SIMS allows for repeatable analyses to capture 1 °C or lower drift in an RTA temperature higher than 1000 °C. The benefit of this SIMS approach has been validated by improvement in the device yield since the implementation of monitoring.

Effect of rapid thermal annealing on microstructure, mechanical and tribological properties of amorphous SiC hard coatings

Herein, a-SiC hard coatings were prepared by pulsed DC magnetron sputtering followed by rapid thermal annealing (RTA) at various temperatures. The influence of the RTA temperature on the coatings’ microstructure, mechanical and tribological properties was investigated. The results show that the surface morphology of a-SiC coatings almost unchanged and remains amorphous within 973 K annealing temperature. The content of sp3 first increases and then decreases with increasing annealing temperature, and reaches the maximum value at 773 K. The hardness (H) and elastic modulus (E) of the a-SiC coatings also increase firstly and then decrease due to the variation of sp3 content, while average friction coefficient decreases first and then increases. As the annealing temperature is 823 K, the maximal H, E of 25.02 GPa, 243.63 GPa are obtained. At 773 K annealing temperature, the minimum friction coefficient of 0.107 is realized, a-SiC coating exhibits higher H/E, H3/E2 and tribological properties.

Optical, morphological and electrical properties of rapid thermally annealed CoPc/n-Ge heterostructures for photodiode applications

Effect of rapid thermal annealing (RTA) temperature on electrical, morphological and optical properties of cobalt phthalocyanine (CoPc)/n-Ge heterostructures is investigated. UV–Vis measurements of as-deposited and annealed CoPc thin films show the presence of Q band transition at 618 nm and 690 nm absorption wavelength suggesting π-π* transitions. A phase transition is evidenced for the 300 °C annealed CoPc sample. Further, no degradation of Q band intensities is noticed which signifies highly stable CoPc thin films even after annealing at 400 °C. AFM measurements of CoPc thin film on Ge substrate reveal an increased RMS roughness with increased annealing temperature until 200 °C and further roughness was found to be decreased for the sample annealed at 300 °C. A clear change in the morphology of CoPc thin films is observed for the 300 °C annealed sample than 200 °C annealed sample which shows an evidence for the phase transition of CoPc thin films from α-phase to β-phase. This phase transition of CoPc thin films was also confirmed using XRD measurements. FESEM with EDS measurements were carried out for the as-deposited and annealed heterostructures. The surface topography of all the samples reveals a spherical-grained morphology and the grains seem to be highly dispersed in 400 °C annealed CoPc/Ge layers. The electrical and current transport mechanisms of the Au/CoPc/n-Ge heterostructure have been explored at different annealing temperatures by using I–V and C–V characteristics. Notably, the results reveal that superior barrier parameters are observed for the heterostructure annealed at 300 °C than as-deposited heterostructure. Rapid thermal annealing of the Au/CoPc/Ge heterostructure shows its promising applications in the areas of optoelectronic or photoresponsive devices.

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.

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.

Rapid Thermal Processing of Kesterite Thin Films

Multinary chalcogenides with Kesterite structure Cu2ZnSn(S,Se)4 (CZTSSe) are a prospective material base for the enhancement of the photovoltaics industry with abundant and environmentally friendly constituents and appropriate electro-physical properties for building highly efficient devices at a low cost with a short energy pay-back time. The actual record efficiency of 13.6%, which was reached recently, is far below the current isostructural chalcopyrite’s solar cells efficiency of near 24%. The main problems for future improvements are the defects in and stability of the Kesterite absorber itself and recombination losses at interfaces at the buffer and back contacts. Here, we present an investigation into the rapid thermal annealing (RTA) of as-electrodeposited thin films of Cu2ZnSnS4 (CZTS). The treatment was carried out in a cold wall tubular reactor in dynamic conditions with variations in the temperature, speed and time of the specific elements of the process. The effect of annealing was investigated by X-ray diffractometry, Raman scattering and Scanning Electron Microscopy (SEM). The phase composition of the films depending on treatment conditions was analyzed, showing that, in a slow, prolonged, high-temperature process, the low-temperature binaries react completely and only Kesterite and ZnS are left. In addition, structural investigations by XRD have shown a gradual decrease in crystallite sizes when the temperature level and duration of the high-temperature segment increases, and respectively increase in the strain due to the formation of the phases in non-equilibrium conditions. However, when the speed of dynamic segments in the process decreases, both the crystallite size and strain of the Kesterite non-monotonically decrease. The grain sizes of Kesterite, presented by SEM investigations, have been shown to increase when the temperature and the duration increase, while the speed decreases, except at higher temperatures of near 750 °C. The set of experiments, following a scrupulous analysis of Raman data, were shown to have the potential to elucidate a way to ensure the fine manipulation of the substitutional Cu/Zn defects in the structure of CZTS thin films, considering the dependences of the ratios of Q = I287/I303 and Q′ = I338/(I366 + I374) on the process variables. Qualitatively, it can be concluded that increases in the speed, duration and temperature of RTA lead to increases in the order of the structure, whereas, at higher temperatures of near 750 °C, these factors decrease.

Structural characteristics and sensing capabilities of stacked Ti/Ni sensitive film for extended-gate field-effect transistor solid-state pH sensors

This study describes a straightforward approach for fabricating stacked Ti/Ni sensitive membranes on n+-type Si substrates using dc sputtering to build solid-state extended-gate field-effect transistor (EGFET) pH sensors. The effects of rapid thermal annealing (RTA) temperature (500–700 °C) and ambient (N2 or O2) on the structural characteristics of stacked Ti/Ni sensitive films were fully explored. We used X-ray photoelectron spectroscopy, secondary ion mass spectroscopy, X-ray diffraction, atomic force microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy to characterize the chemical compositions, element profiles, film structures, surface morphologies, film microstructures, and film compositions of the stacked Ti/Ni sensitive films. The relative structural characteristics of the stacked Ti/Ni sensitive films have a significant impact on their sensing capabilities. The most effective sensing performance, such as pH sensitivity, drift, and hysteresis, was achieved at an RTA temperature of 600 °C and in the presence of N2 gas among various RTA temperatures and annealing ambient. Due to its compact size and strong stability, the stacked Ti/Ni sensitive film shows great potential for use in future pH sensor and biosensor applications.

Simultaneously-doping of HfO2 thin films by Ni with sputtering technique and effect of post annealing on structural and electrical properties

This article reports a detailed structural and electrical characterization study of Ni:HfO2 dielectrics grown by rf and dc sputtering and variations in the rapid thermal annealing temperature. Annealing produced obvious changes in the morphological structure of films and XRD confirmed that the crystallite size increased from 1.3 nm to 14.4 nm with the annealing temperature. XPS showed that the amount of non-lattice oxygen decreased owing to the effects of annealing and resistivity. Dc resistivity measurements showed that the lowest sheet resistance of 1.182 × 106 Ω/□ was achieved by as-deposited films and increased to 70.960 Ω/□ with annealing. Structural differences in films due to the effect of annealing caused equivalent circuit models to vary and different resistance values in electrochemical impedance spectrometry. This study illustrates that HfO2 thin films, boosted by doping and rapid thermal annealing, provide a route toward advanced gate oxide stack structures in electronic devices beyond conventional high-dielectric-constant materials.

Structural properties and sensing performance of Ni–Ti alloy films for extended-gate field-effect transistor pH sensors

This study presents a facile Ni–Ti alloyed film grown on the n+-type Si through a DC sputtering technique for electrochemical pH sensing and its comprehensive structural, morphological, compositional, profiling, microstructural, and elemental characterization. In addition to pH sensing measurements, the properties of the sensing layer were analyzed using X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, secondary ion mass spectroscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy analysis. The impact of rapid thermal annealing (RTA) treatment (500–700 °C) on the alloyed Ni–Ti sensitive films was extensively studied. The structural feature of the alloyed Ni–Ti sensitive films is more closely related to their relative sensing performances. The performance of the alloyed Ni–Ti sensitive film at the RTA temperature of 600 °C showed a higher pH sensitivity of 60.73 mV/pH in a wide pH range of 2–12 in comparison with other RTA temperatures. Moreover, the stability of this 600 °C-annealed EGFET sensor exhibited a small drift rate of 0.21 mV/h in pH 7 and a low hysteresis voltage of 1 mV in a loop of pH 7 → 4→7 → 10→7. The alloyed Ni–Ti sensitive film is fully compatible with a standard CMOS process and demonstrates better sensing performance than other metal nitride sensitive films (e.g. RuN, TiN), suggesting it may be a strong candidate for future sensor and biosensor applications.

Phase evolution in epitaxial Gd2O3 due to anneal temperature for silicon on insulator application

Epitaxial growth of Si on rare-earth oxides on Si wafer using sputter technology promises cheaper and high-volume manufacturing of Silicon-on-insulator (SOI) wafers over costly solutions like the smart-cut method. Further, rapid thermal annealing (RTA) in standard complementary metal–oxide–semiconductor (CMOS) processing affects the performance of SOI substrate through chemical and crystal phase change. Herein, we present a systematic study on the rich physical and chemical phase evolution of epitaxial Gd2O3 grown on Si (111) using RF sputtering subjected to RTA temperatures (850−1050 °C). First, X-ray diffraction analysis shows a significant enhancement of the epitaxial cubic phase in as-deposited Gd2O3 at an optimum RTA temperature of 850 °C, which is partially explained by epitaxial-regrowth of an amorphous layer at Gd2O3/Si interface as observed in Transmission Electron Microscopy. Secondly, the degradation of crystallinity beyond 900 °C is correlated with temperature-dependent Si diffusion into Gd2O3 that becomes observable by X-ray photoelectron spectroscopy. The Gd2O3 crystallinity is completely quenched into the amorphous gadolinium silicate phase at 1050 °C. Eventually, we employed X-ray reflectivity modeling to evaluate the film thickness variation with RTA. This study provides a detailed insight into the structural and chemical dynamics occurring in epitaxial-Gd2O3 film for CMOS-relevant temperatures.

Improved RF power performance of InAlN/GaN HEMT by optimizing rapid thermal annealing process for high-performance low-voltage terminal applications

Improved radio-frequency (RF) power performance of InAlN/GaN high electron mobility transistor (HEMT) is achieved by optimizing the rapid thermal annealing (RTA) process for high-performance low-voltage terminal applications. By optimizing the RTA temperature and time, the optimal annealing condition is found to enable low parasitic resistance and thus a high-performance device. Besides, compared with the non-optimized RTA HEMT, the optimized one demonstrates smoother ohmic metal surface morphology and better heterojunction quality including the less degraded heterojunction sheet resistance and clearer heterojunction interfaces as well as negligible material out-diffusion from the barrier to the channel and buffer. Benefiting from the lowered parasitic resistance, improved maximum output current density of 2279 mA⋅mm−1 and higher peak extrinsic transconductance of 526 mS⋅mm−1 are obtained for the optimized RTA HEMT. In addition, due to the superior heterojunction quality, the optimized HEMT shows reduced off-state leakage current of 7 × 10−3 mA⋅mm−1 and suppressed current collapse of only 4%, compared with those of 1 × 10−1 mA⋅mm−1 and 15% for the non-optimized one. At 8 GHz and V DS of 6 V, a significantly improved power-added efficiency of 62% and output power density of 0.71 W⋅mm−1 are achieved for the optimized HEMT, as the result of the improvement in output current, knee voltage, off-state leakage current, and current collapse, which reveals the tremendous advantage of the optimized RTA HEMT in high-performance low-voltage terminal applications.

Impact of rapid thermal annealing on structural and sensing properties of Ni–Ti sensitive films for extended-gate field-effect transistor pH sensors

In the present work, a facile Ni–Ti film deposited on n+-type Si substrate is introduced as a sensitive film for the development of a solid-state extended-gate field-effect transistor (EGFET) pH sensor. Influence of rapid thermal annealing (RTA) treatment (500–700 °C) on structural properties of the Ni–Ti sensitive films was extensively investigated. The film structures, surface morphologies, element profiles, film microstructures, and chemical compositions of the Ni–Ti sensitive films were characterized by a combination of X-ray diffraction, atomic force microscopy, secondary ion mass spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy, respectively. The structural features of the Ni–Ti sensitive films are most closely related to their sensing characteristics. The experimental results indicated that the Ni–Ti sensitive film annealed at the RTA temperature of 600 °C exhibited better sensing performances (a higher pH sensitivity of 71.01 mV/pH, a lower hysteresis voltage of 1 mV and a smaller drift rate of 0.15 mV/h) than other RTA temperatures. The proposed Ni–Ti sensitive film is expected to be effectively useful for various long-term pH sensor and biosensor applications, since it satisfies the typically required sensing performances such as sensitivity and stability.

Inhibited Degradation of Organic–Inorganic Perovskite-Based Quantum Dot Films via Rapid Annealing Temperatures

General hot-plate heating is used to form a crystal structure of films; however, how to achieve a homogeneous and regulated crystal formation will be a crucial challenge in the future. In this study, based on perovskite-series materials, organic methylamine lead trioxide (MAPbI3) films doped with inorganic lead iodide (CsPbI3) quantum dots (QDs) are treated using the rapid thermal annealing (RTA) process in argon gas to break the crystallization barrier. These RTA-treated perovskite quantum dot (PQD) films at various temperatures of 100–160 °C are detected using X-ray diffraction, X-ray spectroscopy, and absorbance measurements to investigate their structural and optical properties as well as their binding states. The experimental results demonstrate that the PQD film annealed at 120 °C has optimized characteristics, revealing better crystallinity and the lowest content of oxygen atoms (31.4%) and C-O-C bonding (20.1%). A too-high RTA temperature, more than 140 °C, causes severe degradation with the existence of PbI2. A proper RTA process, an alternative to normal heating and annealing, can effectively inhibit the occurrence of degradation and even usefully improve the performance of PQD films.

Regulation of structural, electrical and optical properties of Sb-doped SnO2 films prepared with different O2 flow rates by rapid thermal annealing

Effects of rapid thermal annealing (RTA) on the structure and photoelectric properties of Sb-doped SnO2 (ATO) films have not been systematically reported. In this study, ATO films were prepared by RF magnetron sputtering under different O2 flow rates (0, 15, 30 and 45 sccm), and then were subjected to RTA at different temperatures (400, 600 and 800 °C) in atmospheric environment. The results show that preferred orientations of ATO films changes from (101) to (110) crystal-plane and crystallite size increases with increasing O2 flow rate. RTA cannot change the films’ preferred orientation and crystallite size except for the film deposited in Ar atmosphere (0 sccm O2), but it can decrease the compressive stress in the films. The as-deposited and annealed films with low transmittance in visible light range (TVis) have obvious Raman scattering peak, and scattering peak of Eg vibration mode is stronger in the appearing Raman scattering peaks. Increasing O2 flow rate degrades electrically conductive properties of the films, increases TVis and makes optical band-gap (Eopt) first increase and then decrease. With increasing RTA temperature, the electrically conductive properties enhance and Eopt increases for the films deposited with all O2 flow rates, but TVis basically decreases for the films deposited with O2 flow rate of 15–45 sccm. Currently, the ATO film deposited at 15 sccm O2 and annealed at 600 °C has the best transparent conductive properties (the resistivity, sheet resistance, TVis and figure of merit are 2.09 × 10−3 Ω cm, 67 Ω/sq., 77.12%, and 1.11 × 10−3 Ω−1, respectively). In addition, element chemical states and point defects in the films were analyzed by XPS. Meanwhile, influence mechanisms of O2 flow rate and RTA on structure and properties of the films were discussed.

Effect of Rapid Thermal Annealing on Material, Electrical, and Sensing Characteristics of Ag-Doped CaTiO3-CuO Thin Film Carbon-Dioxide Gas Sensors

The effect of rapid thermal annealing (RTA) on CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sensing characteristics of RF-sputtered and Ag-doped CaTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -CuO thin films has been studied in this work. The surface morphology, grain size, surface chemical states, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I–V</i> characteristics, and sensing ability of the films, have been evaluated for postdeposition RTA at different temperatures (400 °C–600 °C) and time (0–60 s). As the annealing temperature was raised, crystallinity improved and the grain size increased. Indeed, XRD revealed that RTA resulted in strong crystallographic orientation in the films. XPS analysis revealed no changes in the oxidation states and chemical composition of the material. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I–V</i> measurements show that the resistance of the film decreases as RTA temperature increases. On the other hand, the sensing characteristics reveal an optimum grain size for the best sensitivity. The films annealed at 500 °C for 60 s, leading to a grain size of about 10 nm, display the highest sensor response of 54%, when exposed to 1000 ppm of CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> .

Lead-Free Piezoelectric Ceramic Micro-Pressure Thick Films

In this study, non-stoichiometry lead-free piezoelectric ceramic Li0.058(K0.48Na0.535)0.966(Nb0.9Ta0.1)O3 (LKNNT) thick films were deposited on Pt/Ti/Si substrates using spin-coating method technology to form a LKNNT/Pt/Ti/Si structure of the micro-pressure thick films. Additionally, the influence on the crystalline properties, surface microstructure images, and mechanical properties, and the piezoelectric properties of the non-stoichiometry lead-free piezoelectric ceramic Li0.058(K0.48Na0.535)0.966(Nb0.9Ta0.1)O3 (LKNNT) thick films were observed, analyzed, and calculated using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), focused ion beam (FIB) microscopy, nano-indention technology, and other instruments. This study was divided into two parts: The first part was the investigation into the fabrication parameters and properties of the bottom layer (Pt) and buffer layer (Ti). The Pt/Ti/Si structures were achieved by the DC sputtering method, and then the rapid thermal annealing (RTA) post-treatment process was used to re-arrange the grains and reduce defects in the lead-free Li0.058(K0.48Na0.535)0.966(Nb0.9Ta0.1)O3 (LKNNT) thick films. In the second part, lead-free Li0.058(K0.48Na0.535)0.966(Nb0.9Ta0.1)O3 (LKNNT) powder was prepared by the solid-state reaction method, and then acetic acid (C2H4O2) solvent was added to form a slurry for spin-coating technology processing. The fabrication parameters, thick film micro-structure, crystalline properties, nano-indention technology, and the piezoelectric coefficient characteristics of the developed lead-free Li0.058(K0.48Na0.535)0.966(Nb0.9Ta0.1)O3 (LKNNT)/Pt/Ti/Si structure of the micro-pressure thick film devices a were investigated. According to the experimental results, the optimal fabrication processing parameters of the lead-free Li0.058(K0.48Na0.535)0.966(Nb0.9Ta0.1)O3 (LKNNT) were an RTA temperature of 500 °C, a Ti buffer-layer thickness of 273.9 nm, a Pt bottom electrode-layer thickness of 376.6 nm, a theoretical density of LKNNT of 4.789 g/cm3, a lattice constant of 3.968 × 10−8 cm, and a d33 value of 150 pm/V. Finally, regarding the mechanical properties of the micro-pressure devices for when a microforce of 3 mN was applied, the thick film revealed a hardness of 60 MPa, a Young’s modulus of 13 GPa, and an elasticity interval of 1.25 μm, which are suitable for future applications of micro-pressure devices.

Activation Enhancement and Grain Size Improvement for Poly-Si Channel Vertical Transistor by Laser Thermal Annealing in 3D NAND Flash.

The bit density is generally increased by stacking more layers in 3D NAND Flash. Lowering dopant activation of select transistors results from complex integrated processes. To improve channel dopant activation, the test structure of vertical channel transistors was used to investigate the influence of laser thermal annealing on dopant activation. The activation of channel doping by different thermal annealing methods was compared. The laser thermal annealing enhanced the channel activation rate by at least 23% more than limited temperature rapid thermal annealing. We then comprehensively explore the laser thermal annealing energy density on the influence of Poly-Si grain size and device performance. A clear correlation between grain size mean and grain size sigma, large grain size mean and sigma with large laser thermal annealing energy density. Large laser thermal annealing energy density leads to tightening threshold voltage and subthreshold swing distribution since Poly-Si grain size regrows for better grain size distribution with local grains optimization. As an enabler for next-generation technologies, laser thermal annealing will be highly applied in 3D NAND Flash for better device performance with stacking more layers, and opening new opportunities of novel 3D architectures in the semiconductor industry.

Effects of transition metal dopants (Mo and W) on electrical and optical properties of CdO thin films

Cadmium oxide (CdO) is known to have the highest electron mobility among common transparent conductive oxides (TCOs). Here, we carried out a systematic investigation on the properties of CdO films doped with transition metal donors, namely Mo (CMO) and W (CWO) which have been reported to enhance the mobility in In2O3. We find that the electron concentration N in as-grown CMO and CWO increases with dopant concentration to> 1021 cm−3. While the mobility μ increases with rapid thermal annealing (RTA) temperature, N decreases when the temperature is> 400 °C, suggesting that Mo and W are unstable donors. The stronger affinity of the Mo and W to diffuse out in an O2 environment results in an even stronger decrease in N when annealed in O2. Isothermal RTA at 300 °C further reveals that H interstitial donors incorporated during room temperature film growth are unstable at temperature< 300 °C. Overall, both CMO and CWO can achieve a low resistivity of ∼1.5 × 10−4 Ω-cm with μ > 100 cm2/V-s and N∼3.5 × 1020 and 4 × 1020 cm–3, respectively, as well as an overall transmittance> 80% up to λ > 1600 nm with x ≲ 0.01 after RTA at 600 °C in N2. Finally, changes in optical absorption edges Eopt of CMO and CWO are consistent with the modification of the conduction band (CB) due to anticrossing interactions of the dopant d–states with the CdO CB, which also flattens the CB dispersion which dramatically lowers the μ at high x.

Effects of rapid thermal annealing temperature on NO2 gas sensing properties of p-type mixed phase tin oxide thin films

Effects of the rapid thermal annealing (RTA) temperature on the NO2 gas sensing properties of p-type SnOX thin films were investigated. The SnOX thin films were deposited using radio-frequency magnetron sputtering and subjected to RTA at 200 °C, 250 °C, and 300 °C. The deposited SnOX thin films contained both p-type SnO and n-type SnO2 components, but the SnO was the dominant phase. The amount of SnO2 components increased with increasing RTA temperature, but the highest amount of oxygen vacancy (OVac) states was observed in the SnOX thin film annealed at 250 °C. The surface roughness of the SnOX thin film decreased as the RTA temperature increased. The SnOX thin film subjected to RTA at 250 °C exhibited a significantly higher maximum sensing response to NO2 (4.25–10 ppm NO2 at 60 °C) than those of the films treated at 200 °C (1.13) or 300 °C (0.92). The higher response was attributed to the larger amount of SnO2 and OVac in the thin film and large number of defects and cracks on the film surface. The experimental results demonstrated that the post-deposition RTA temperature considerably affects the NO2 sensing properties of the p-type SnOX-based gas sensors.

Recrystallization model of discrete amorphous regions in C3H5-molecular-ion-implanted silicon substrate surface analyzed by X-ray photoelectron spectroscopy

We investigated the recrystallization of discrete amorphous regions formed in a C3H5-molecular-ion-implanted silicon (Si) substrate surface in the rapid thermal annealing (RTA). The change in the crystalline fraction of the C3H5-molecular-ion-implanted substrate surface after the RTA was obtained from the chemical shifts of Si 2p spectra by X-ray photoelectron spectroscopy. We found that the crystalline fraction increases depending on the RTA temperature after an incubation period. The transformation from the amorphous phase to the crystalline phase was analyzed on the basis of the Johnson–Mehl–Avrami–Kolmogorov theory. It was revealed that recrystallization of discrete amorphous regions proceeded three-dimensionally and activation energy was estimated to be 2.74 ± 0.39 eV, which is approximately equal to 2.70 eV for the solid-phase epitaxy of the continuous amorphous layer in a Si crystal. Therefore, we believe that discrete amorphous regions are recrystallized via solid-phase epitaxy laterally and vertically from the amorphous/crystal interface around them.