Rapid Thermal Annealing Treatment Research Articles

Optimization of p-type contact for electrical injection and light extraction for 365 nm UV-A LEDs

This paper demonstrates low-resistance and high-transparency p-type contact materials for ultraviolet (UV) micro-light-emitting diodes (LEDs) at 365 nm. As a commonly used p-type LED contact, indium tin oxide (ITO) and nickel/ITO (Ni/ITO) contacts were studied before and after rapid thermal annealing (RTA) treatments. The transmittance at 365 nm wavelength of 200 nm thick ITO films increased from approximately 57%–90% after RTA at a temperature exceeding 400 °C, while the Ni/ITO film had a transmittance of about 73% after annealing. Micron-sized UV-LEDs with Ni/ITO p-contact were fabricated. Electrical characterization shows that Ni/ITO films annealed at 600 °C demonstrated good ohmic contact behavior and the highest on-wafer external quantum efficiency, despite slightly lower transmittance. This paper shows the potential of annealed Ni/ITO films as promising p-contact materials for high-performance 365 nm UV-LEDs.

Effects of ion implantation with arsenic and boron in germanium-tin layers

Ion implantation is widely used in the complementary metal–oxide–semiconductor process, which stimulates to study its role for doping control in rapidly emerging group IV Ge1−xSnx materials. We tested the impact of As and B implantation and of subsequent rapid thermal annealing (RTA) on the damage formation and healing of the Ge1−xSnx lattice. Ion implantation was done at 30, 40, and 150 keV and with various doses. The implantation profiles were confirmed using secondary ion mass spectrometry. X-ray diffraction in combination with Raman and photoluminescence spectroscopies indicated notable crystal damage with the increase of the implantation dose and energy. Significant damage recovery was confirmed after RTA treatment at 300 °C and to a larger extent at 400 °C for a Ge1−xSnx sample with Sn content less than 11%. A GeSn NP diode was fabricated after ion implantation. The device showed rectifying current-voltage characteristics with maximum responsivity and detectivity of 1.29 × 10−3 A/W and 3.0 × 106 cm (Hz)1/2/W at 77 K, respectively.

Optimization of transparent conductive properties of magnetron sputtered Sb-doped SnO2 films by RF power: Towards application in polymer-dispersed liquid crystal (PDLC) films

Sb-doped SnO2 (ATO) films were prepared with different RF powers (PRF) under two O2 flow rates (FO2) by magnetron sputtering, and then subjected to rapid thermal annealing (RTA) treatment. The effects of PRF, FO2, and RTA on the crystallinity, stress, surface morphology, conductive properties, transmittance in visible-light range (TVis), and energy gap (Eg) of the films were investigated. As the PRF increases, the film crystallinity improves or first improves and then slightly degrades, and the compressive stress decreases. With increasing PRF, the surface changes from textured to granular morphology and from granular to honeycomb-like morphology under two FO2, respectively. Meanwhile, the conductive properties first enhance and then degrade, and the TVis and Eg tend to decrease, especially at higher PRF. Basically, the films prepared with higher FO2 have lower compressive stress, inferior conductive properties, and larger TVis and Eg compared with the films prepared with lower FO2. After RTA, the film crystallinity obviously improves, the compressive stress transforms into tensile stress, and the surface morphology has not undergone significant changes. Meanwhile, the conductive properties significantly enhance and Eg obviously increases. The TVis of the films prepared with lower FO2 can be increased by RTA. The influence mechanisms of the above factors on the structure and optoelectronic properties of the ATO films were explored, and ultimately, the ATO films have the TVis of 76.35–80.86%, sheet resistance of 51.7–91.9 Ω/sq., and quality factor of 1.03–1.67 × 10−3 Ω−1 within the optimized PRF range. Polymer-dispersed liquid crystal (PDLC) films were fabricated using optimized performance ATO films as electrodes, and their on-state transmittance, off-state transmittance, threshold electric field, and saturation electric field were 2.08–4.61%, 61.69–68.56%, 0.656–0.796 V/μm, and 1.68–2.108 V/μm, respectively. The current results indicate the potential application of ATO films in PDLC films as electrode.

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.

Enhanced emission from hBN in sputtered microcavities.

In this observational study, we embed few-layer hexagonal boron nitride (hBN) inside a planar Fabry-Perot cavity fabricated using a pulsed DC magnetron sputtering system and show that the hBN retains its inherent visible range, defect-based luminescent properties following relatively energetic deposition processing. The observed surface-normal emission enhancement factor of ∼40 is in good agreement with theoretical predictions. We also found that embedded hBN subjected to a rapid thermal annealing treatment exhibits a cracking effect where the edges of the material glow distinctly brighter than adjacent regions. Our results might inform future efforts involving monolithic integration of hBN active layers.

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.

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.

Ge-ion implantation and activation in (100) β-Ga2O3 for ohmic contact improvement using pulsed rapid thermal annealing

In this work, we analyze the optimum annealing conditions for the activation of Ge-implanted β-Ga2O3 in order to reach low ohmic contact resistances. The experiments involved the use of a pulsed rapid thermal annealing treatment at temperatures between 900 and 1200 °C in nitrogen atmosphere. Our investigations show remarkable changes in the surface morphology involving increased surface roughness after high-temperature annealing above 1000 °C as well as a significant redistribution of the implanted Ge. Nevertheless, the specific contact resistance is strongly reduced by one order of magnitude after annealing at 1100 °C, reaching a record value of 4.8 × 10−7 Ω cm2 at an implantation activation efficiency of 14.2%. The highest activation efficiency of 19.2% and lowest sheet resistances were reached upon annealing at 1200 °C, which, in turn, showed inferior ohmic contact properties due to a severe increase of the surface roughness. Our results verify the high potential of applying high-temperature annealing processes above 1000 °C after Ge implantation for reaching low ohmic contact resistances to β-Ga2O3.

External Fields Assisted Highly Efficient Oxygen Evolution Reaction of Confined 1T-VSe2 Ferromagnetic Nanoparticles.

As a clean and effective approach, the introduction of external magnetic fields to improve the performance of catalysts has attracted extensive attention. Owing to its room-temperature ferromagnetism, chemical stability, and earth abundance, VSe2 is expected to be a promising and cost-effective ferromagnetic electrocatalyst for the accomplishment of high-efficient spin-related OER kinetics. In this work, a facile pulsed laser deposition (PLD) method combined with rapid thermal annealing (RTA) treatment is used to successfully confine monodispersed 1T-VSe2 nanoparticles in amorphous carbon matrix. As expected, with external magnetic fields of 800 mT stimulation, the confined 1T-VSe2 nanoparticles exhibit highly efficient oxygen evolution reaction (OER) catalytic activity with an overpotential of 228mV for 10mA cm-2 and remarkable durability without deactivation after >100h OER operation. The experimental results together with theoretical calculations illustrate that magnetic fields can facilitate the surface charge transfer dynamics of 1T-VSe2 , and modify the adsorption-free energy of *OOH, thus finally improving the intrinsic activity of the catalysts. This work realizes the application of ferromagnetic VSe2 electrocatalyst in highly efficient spin-dependent OER kinetics, which is expected to promote the application of transition metal chalcogenides (TMCs) in external magnetic field-assisted electrocatalysis.

Activation of Mg impurities in epitaxial p-GaN with rapid thermal annealing assisted supercritical fluid treatment

The activation of an Mg acceptor in p-GaN with rapid thermal annealing (RTA) assisted low-temperature supercritical fluid (SCF) treatment (RTA-A-SCF) was investigated. After RTA-A-SCF treatment, the luminescence band of the N vacancy in the PL spectra was significantly suppressed. An evident decrease in H concentration is also observed in secondary ion mass spectrometer measurements, it indicates an obvious decrease of Mg–H complexes in the p-GaN. In addition, the ohmic contacts have been well improved and the hole concentration has increased by an order of magnitude. The activation mechanism of RTA-A-SCF treatment was further analyzed by X-ray photoelectron spectroscopy.

Single Crystalline Transparent Conducting F, Al, and Ga Co-Doped ZnO Thin Films with High Photoelectrical Performance.

Transparent conductive film (TCF) is a material that integrates electrical conductivity and optical transparency. It is widely used as an electrode material in thin-film solar cells. However, considerable progress is needed to facilitate its high performance and low-cost preparation. In this study, a preparation scheme for AlF3 and GaF3 co-doped ZnO (FAGZO) thin films was designed and implemented by magnetron sputtering (MS). The mutual restraint between the electrical properties and the wide-spectrum transmission performance of ZnO films was resolved. First-principles calculations showed that the doped ZnO system had n-type conductivity and that the most stable structure was the FO-AlZn-GaZn system. The experimental results verified the theoretical predictions. Single crystalline ZnO transparent conducting films (ZnO-TCFs) of high quality were achieved by MS. After rapid thermal annealing (RTA) treatment, the mobility reached 49.6 cm2/V s, and the resistivity decreased to 3.82 × 10-4 Ω cm. The AT was 90% between 380 and 1200 nm. Furthermore, the application of the prepared FAGZO film in perovskite solar cells (PSCs) has been verified. Compared to the reference indium tin oxide film, the PSCs using the FAGZO film showed higher JSC and power conversion efficiency. These results demonstrate that MS combined with anion and cation co-doping provides an effective means of exploring high-quality and high-performance ZnO-TCFs.

Excellent Uniformity and Properties of Micro-Meter Thick Lead Zirconate Titanate Coatings with Rapid Thermal Annealing.

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.

Fabrication of thin ferroelectric Hf0.5Zr0.5O2 films by millisecond flash lamp annealing

We used millisecond flash lamp annealing (FLA) to form thin ferroelectric Hf0.5Zr0.5O2 (HZO) films with thicknesses of less than 10 nm and with remanent polarization up to 30 μC cm−2. A clear dependency of the polarization on the annealing temperature and time was observed, indicating that the precise management of the thermal budget is a key factor in forming ferroelectric HZO. We also show and compare the process windows within which ferroelectricity in 10 and 5 nm samples is obtained. The results show that a high thermal budget is necessary for thinner samples. We examined the endurance characteristics and a greater endurance compared to rapid thermal annealing treatment was observed with more than 1010 cycles without breakdown confirmed in 5 nm thick samples. The data indicates that there is the possibility of further thickness scaling whilst retaining highly durable characteristics for films annealed by FLA.

Mechanical Properties, Biocompatibility and Antibacterial Behaviors of TaO0.2N0.8 and TaO0.2N0.8-Ag Nanocomposite Thin Coatings

TaOx = 0.2Ny = 0.8 was reported previously to have the highest modulus (E), hardness (H), and H to E ratio attributed to the embedment of substituting oxygen atoms in the TaN crystal structure, among some TaOxNy coatings studied. In the present study, TaO0.2N0.8-Ag nanocomposite coatings were fabricated by reactive multi-target sputtering with O/N ratio adjusted to the expected value. The various Ag contents were doped to induce antibacterial behaviors. After deposition and annealing with rapid thermal process (RTP) at 400 °C for 4 min, the coatings’ mechanical and structural properties were studied. After these examinations, the samples were then studied for their cell attachment, cell viability, and biocompatibility with 3-T-3 cells, as well as for their antibacterial behaviors against Escherichia coli. It appeared that hardness and crack resistance could be improved further with suitable amount of Ag doped to the coatings, followed by rapid thermal annealing treatment. The coating with 1.5 at. % Ag had the highest hardness and good H/E ratio. It was also found that the antibacterial efficiency of TaO0.2N0.8-Ag coatings could be much improved, comparing with that of TaO0.2N0.8 coatings. The antibacterial efficiency increased with the increased Ag contents. There was no negative effect of Ag on the biocompatibility of TaO0.2N0.8-Ag. Through the cell attachment and viability testing using MTT(3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, it can be summarized that surface roughness could be the dominating factor for cell viability and attachment, which means the improvement of biocompatibility. Accordingly, the samples with 1.5 at. % and 11.0 at. % Ag show the best biocompatibility. The variation of surface roughness was affected by the incorporation of Ag and oxygen atoms after rapid thermal annealing.

Enhancing the p-type conductivity of pure phase SnO via stoichiometry control and annealing

While n-type transparent conducting oxides (TCOs) have been well developed and widely used in optoelectronic devices, the availability of high-performance p-type TCOs is still scarce which in turn hinders the further advancement of oxide based transparent optoelectronic devices. Unlike the most widely used p-type NiO, Tin monoxide (SnO) has a relatively delocalized valence band, which leads to a high hole mobility of >1 cm2/Vs. In this work, we enhance the p-type conductivity of SnO thin films by tunning the oxide stoichiometry through adjusting the growth conditions and post-growth rapid thermal annealing (RTA) treatment. Specifically, we synthesized nominally undoped Sn-rich SnO (SnO1-δ) thin films by co-sputtering an SnO target and a metallic Sn target and control the film stoichiometry by varying the sputter power of the Sn target so that SnO1-δ films with excess Sn (δ) varying from 0 to ∼5% was incorporated. We find that the addition of dilute amount of excess Sn is an effective approach to regulate the film stoichiometry so that a low p-type resistivity can be achieved after post-growth RTA. All as-grown films are amorphous and after RTA exhibit a polycrystalline tetragonal structure, with p-type resistivity decreases with increasing δ. However, metallic β-Sn clusters are formed for films with δ≳ 0.05. The presence of these β-Sn clusters results in a degraded optical transmittance by ∼10% in the visible range. With δ∼0.03 in the as-grown film, a p-type pure phase SnO film with a low resistivity of ∼0.5 Ω−cm, and a decent visible transparency of ∼60% is achieved after 300 °C RTA in N2. This p-type SnO has a wide band gap of 2.8 eV with a high valence band maximum (VBM) located in the range of 4.6–4.8 eV below the vacuum level, making it suitable for many device applications, particularly as hole transport layers in optoelectronic devices.

Performance evaluation of transparent self-powered n-ZnO/p-NiO heterojunction ultraviolet photosensors

We have constructed NiO/ZnO thin film heterojunction diodes by dc magnetron sputtering technique and evaluated their performance for ultraviolet sensor applications. The constructed device configuration, ITO/ZnO/NiO/Ag exhibited excellent current-voltage rectifying characteristics in the order of 10 5 at room temperature. The effect of rapid thermal annealing treatment on the fabricated ITO/ZnO/NiO thin film stack was evaluated for their photodetector characteristics. The structural, optical, and spectroscopic properties were also investigated. Further, the ITO/ZnO/NiO/Ag diodes were tested under 365 nm UV light illumination having a power density of 0.06 mW/cm 2 . Remarkably, a speed of response with rise/fall time of 197.29/537.10 ms has been recorded at self-powered mode. Interestingly, the photodiode device has exhibited a spectral responsivity of 13.01 mA/W and stable photo detectivity of 5.66 × 10 11 Jones at room temperature. The n-ZnO/p-NiO heterojunction photodetector has shown its ability to detect a faint UV light in a self-powered mode. • Fabricated transparent p-NiO/n-ZnO heterojunction by dc magnetron sputtering with an excellent photo-to-dark current ratio. • It operated in a self-powered mode under 365 nm wavelength of a low optical power source i.e., 0.06 mW/cm 2 . • Achieved excellent speed of response of rising and fall time of 197.29 ms and 537.10 ms respectively. • At Zero bias, responsivity varied from 13.01 mA/W to 6.52 mA/W and EQE 4.42 % to 2.21 % as a function of rapid thermal annealing.

Ferroelectricity induced double-direction conductance modulation in Hf x Zr1−x O2 capacitors

The artificial synapses are basic units in the hardware implementation of neuromorphic computing, whose performances should be gradually modulated under external stimuli. The underlying mechanism of the increasing and decreasing device conductance is still unclear in the Hf0.5Zr0.5O2 based synapses. In this study, the Hf0.5Zr0.5O2 capacitors with different stack orders are fabricated in atomic layer deposition, whose ferroelectric properties are investigated by analyzing the capacitance–voltage and polarization-voltage curves. The enhanced ferroelectricity is found after the rapid thermal annealing treatment for all the TiN/Hf0.5Zr0.5O2/TiN, TiN/HfO2-ZrO2/TiN and TiN/ZrO2-HfO2/TiN devices. In the device with poor ferroelectricity, the conductance gradually decreases under both positive and negative identical pulse schemes, which corresponds to the gradual dissolution process of the conductive filaments established in the initial pulse. For the capacitors with strong ferroelectricity, dual-direction conductance modulation can be observed due to the partial domain switching process, which can emulate the potentiation and depression process of biological synapses.

Resonant Raman Scattering in Boron-Implanted GaN.

A small Boron ion (B-ion) dose of 5 × 1014 cm−2 was implanted in a GaN epilayer at an energy of 50 keV, and the sample was subjected to high-temperature rapid thermal annealing (RTA). The resonant Raman spectrum (RRS) showed a strong characteristic of a photoluminescence (PL) emission peak associated with GaN before B-ion implantation and RTA treatment. The PL signal decreased significantly after the B-ion implantation and RTA treatment. The analysis of temperature-dependent Raman spectroscopy data indicated the activation of two transitions in B-ion-implanted GaN in different temperature ranges with activation energies of 66 and 116 meV. The transition energies were estimated in the range of 3.357–3.449 eV through calculations. This paper introduces a calculation method that can be used to calculate the activation and transition energies, and it further highlights the strong influence of B-ion implantation on the luminesce of GaN.

Structural properties and sensing performance of TaOx/Ta stacked sensing films for extended-gate field-effect transistor pH sensors

In this article, the TaOx/Ta stacked sensing films as sensing membranes were deposited onto n+-type Si substrate by a radio-frequency (RF) magnetron sputtering technique for solid-state extended-gate field-effect transistor (EGFET) pH sensors. The effect of rapid thermal annealing (RTA) treatment (300–700 °C) on structural properties of the TaOx/Ta stacked sensing films was investigated in detail. The chemical compositions, element profiles, crystallographic structures, surface morphologies, and film microstructures of the TaOx/Ta stacked sensing films were characterized by X-ray photoelectron spectroscopy, Auger electron spectroscopy, X-ray diffraction, atomic force microscopy, and transmission electron microscopy, respectively. The sensing performance of the TaOx/Ta stacked sensing films is most closely correlated with their relative structural features. Among these RTA temperatures, the best sensing performance including pH sensitivity, hysteresis and drift was achieved at the RTA temperature of 500 °C. The obtained experimental results showed that the TaOx/Ta stacked sensing film is considered a feasible alternative for pH sensor and biosensor applications.

Conductivity Improvement of Spherical Nano-Crystalline ZnO:Bi/Indium Tin Oxide Layer for Low Cost of Semiconductor Devices

In this work, rapid thermal annealing (RTA) was applied to multi-zinc oxide with doped bismuth layers (ZnO:Bi) on indium tin oxide substrate in the ambient atmosphere resulting in significant improvement of the conductive of multi- ZnO:Bi layers/ITO films. ITO is commonly used as conductive transparent electrodes for an electron transport layer (ETL) of perovskite solar cells. Spherical nano-crystalline ZnO:Bi film was obtained at 520 °C that inevitably affects unstable ITO conductivity. RTA process was subjected at varying conditions (700-930 °C for 20 s). It is found that the RTA process can obtain ZnO:Bi nanostructure, good optical property, and ITO conductivity improvement, simultaneously. The surface morphology of nc-ZnO:Bi films with a 10-20nm diameter size provide low reflectance and high transmittance at 3% and 90%, respectively, in the light wavelength between 250-850 nm. Highly conductive spherical nc-ZnO:Bi multilayers and stable conductivity ITO were obtained after RTA treatment. Thus, the high quality of such spherical nc-ZnO:Bi/ITO films could be used to produce ETL layer for further emerging solar cells and transparent contact electrodes for low-cost semiconductor devices.