Effect Of Rapid Thermal Annealing Research Articles

Enhancing the sensing behavior of a reduced graphene magnetite-based plasmonic optical fiber sensor.

The D-shaped optical fiber is a base for the magnetite-based graphene nanocomposite (rGO/Fe3O4) for a Pb heavy metal sensing layer. The designed sensor was studied under the effects of rapid annealing, water circulation, and plasmonic tuning. Various annealing temperatures (100°C, 200°C, 300°C, and 400°C) were investigated. The effect of rapid thermal annealing (RTA) temperature on the transmission results were found at a short wavelength of 300 nm and a minimum point of ∼380nm. The bandgap energy was verified between 2.3 and 3.17 eV for 100°C and 400°C, respectively. The sensor results show modification toward a short wavelength by increasing the rapid annealing temperature. Compared with furnace methods, the transmittance shift of the plasmonic effect showed the best performance under the influence of RTA. RTA at 300°C and 400°C offered an acceptable degree of stability at the beginning (1-50 min). The best performance of the proposed sensor was improved by introducing a circulating liquid chamber into the initial design. The resonance shifts due to Pb ion concentration (5, 10, and 15 ppm) were studied for transmission and wavelength shifts. The sensor shift was enhanced by using a free space polarizer controller attached to the second design. The results give detection and sensing potential in the visible range at a possible remarkable response time. The figure of merit was 62.5 a.u., and the maximum sensitivity was 1 a.u./ppm by using a polarizer controller. This article presents the optical characterizations of plasmonic sensor-based rGO/Fe3O4 for detecting Pb ions and enhancing the resonance shift. RTA for composite material and water circulation associated with D-shaped optical fiber enhances response time and stability designed using a polarizer controller.

Improving the performance of GaInP solar cells through rapid thermal annealing and delta doping

We show that the effect of rapid thermal annealing (RTA) on carrier lifetime in GaInP grown by molecular beam epitaxy depends strongly on both doping type and density, and that these disparities must be accounted for to realize high-performance GaInP solar cells. Although the photoluminescence intensity and lifetime of lightly doped p- and n-GaInP improved greatly with RTA, heavily doped n + -GaInP showed sharp degradation upon RTA, preventing the realization of GaInP front-junction solar cells with low emitter sheet resistance. Since a low series resistance is important to achieve high fill factor (FF), we designed a front-junction cell utilizing a thin, lightly doped n-type emitter with delta doping to enhance conductivity, attaining an open-circuit voltage (V OC ) of 1.40 V and FF of 86%. We then designed rear-heterojunction solar cells to further leverage the relatively long lifetime of lightly n-doped GaInP (∼19 ns). With the help of delta doping in the n-AlInP window to improve surface passivation, we attained a V OC of 1.42 V, similar to cells grown by metal-organic vapor phase epitaxy. • Rapid thermal annealing greatly improves luminescence of lightly doped n- and p-GaInP but degrades heavily doped n + -GaInP. • We demonstrate front-junction cells with V OC = 1.40 V, the highest value for cells grown by molecular beam epitaxy (MBE). • We present the first rear-junction GaInP solar cells grown by MBE with V OC of 1.42 V; delta doping the window improves surface passivation.

Optical and electronic effects of rapid thermal annealing at Ir–Ga2O3 interfaces

Ir is a common impurity in the edge-defined film-fed growth method used to produce high-power Ga2O3 device structures and growth substrates; yet, the effects of this deep level defect on carrier transport and recombination, particularly at high device processing and operating temperatures and at metal interfaces, have yet to be explored. The optical and electronic nature of Ir in Ga2O3 and at Ir/ Ga2O3 interfaces change on a near-nanometer to micrometer scale after nitrogen rapid thermal annealing; the understanding and control of which could lower defect-assisted tunneling, improve diode rectification, and preserve critical electric field strength. Depth-resolved cathodoluminescence spectroscopy, interface electronic current, and capacitance–voltage measurements reveal how this dominant impurity in bulk, edge-fed crystal growth diffuses, evolves with temperature, and impacts defect formation and Schottky barrier formation.

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.

Influence of rapid thermal annealing on the distribution of nitrogen atoms in GaAsN/GaAs

The article investigates the effect of rapid thermal annealing of ternary GaAs1-xNx/GaAs solid solutions on the distribution of nitrogen atoms in the crystal lattice. The samples are studied by photoluminescence spectroscopy and high-resolution X-ray diffractometry. Due to the size and electronegativity mismatch of nitrogen and arsenic atoms, nitrogen is incorporated unevenly into the GaAs crystal lattice. Options of the nitrogen atoms arrangement in the GaAs crystal lattice before and after rapid thermal annealing are shown. Keywords: dilute nitrides, heterostructures, molecular-beam epitaxy, GaAs, nitrogen.

Investigation of the Effects of Rapid Thermal Annealing on the Electron Transport Mechanism in Nitrogen-Doped ZnO Thin Films Grown by RF Magnetron Sputtering.

Nitrogen-doped ZnO (ZnO:N) thin films, deposited on Si(100) substrates by RF magnetron sputtering in a gas mixture of argon, oxygen, and nitrogen at different ratios followed by Rapid Thermal Annealing (RTA) at 400 °C and 550 °C, were studied in the present work. Raman and photoluminescence spectroscopic analyses showed that introduction of N into the ZnO matrix generated defects related to oxygen and zinc vacancies and interstitials. These defects were deep levels which contributed to the electron transport properties of the ZnO:N films, studied by analyzing the current–voltage characteristics of metal–insulator–semiconductor structures with ZnO:N films, measured at 298 and 77 K. At the appliedtechnological conditions of deposition and subsequent RTA at 400 °C n-type ZnO:N films were formed, while RTA at 550 °C transformed the n-ZnO:N films to p-ZnO:N ones. The charge transport in both types of ZnO:N films was carried out via deep levels in the ZnO energy gap. The density of the deep levels was in the order of 1019 cm−3. In the temperature range of 77–298 K, the electron transport mechanism in the ZnO:N films was predominantly intertrap tunneling, but thermally activated hopping also took place.

Comparative Study of High-Temperature Annealed and RTA Process β-Ga2O3 Thin Film by Sol–Gel Process

As a wide energy band gap semiconductor, a Ga2O3 thin film was prepared by the sol–gel process with different annealing processes. Since Ga2O3 is a type of metal oxide structure, an oxygen annealing process can be considered to remove oxygen defects. An effective oxygen annealing process can help form a β-Ga2O3 structure with reduced defects. In this study, different types of annealing effects for β-Ga2O3 were investigated and compared. An electric furnace process using thermal effect characteristics of and an Rapid Thermal Annealing (RTA) process applied with an infrared radiation light source were compared. Two and 4 h thermal annealing processes were conducted at 900 °C in the furnace. Meanwhile, to study the optical annealing effects, 2 h furnace at 900 °C + 15 min in rapid thermal annealing and only 15 min in rapid thermal annealing effects were compared, respectively. Through increasing the thermal annealing temperature and time, β-Ga2O3 can be formed even though a sol–gel process was employed in this experiment. An annealing temperature of at least 900 °C was required to form β-Ga2O3 thin film. Moreover, by introducing an RTA process just after the spinning process of thin film, a β-Ga2O3 thin film was formed on the sapphire substrates. Compared with the electric furnace process applied for 2 h, the RTA process performed in 15 min has a relatively short process time and results in similar structural and optical characteristics of a thin film. From the X-ray diffraction patterns and UV spectrometer analysis, optically annealed β-Ga2O3 thin films on the sapphire substrate showed a highly crystalized structure with a wide energy band gap of 4.8 eV.

Role and optimization of thermal rapid annealing in Ta/TaOx/Ru based resistive switching memory

The performance of resistive switching (RS) device based on sandwich structure is greatly affected by the characteristics of the RS layer, electrode, and interface. In this work, the effect of rapid thermal annealing (RTA) (300 °C for 120 s) on the RS performance of Ta/TaOx/Ru device was investigated. The discrete distribution in high resistance state (HRS) and low resistance state (LRS) was suppressed after RTA. Meanwhile, the endurance in oxygen RTA is higher 104 times than that of vacuum RTA. The optimized oxygen RTA is contributed to change the microstructure of TaOx (amorphous to nanocrystal), providing the local conductive path, and implant oxygens in top electrode (TE) Ta, acting as an oxygen source (reservoir). It is shown that the nanocrystal TaOx and the oxygen content in TE are intrinsically crucial to the RS behavior and the simple low temperature oxygen RTA is a powerful technique to optimize the RS performance.

Effects of rapid thermal annealing on the properties of room-temperature oxygenated DC sputtered zinc thin films for CZTS solar cells application

This work investigated the potential to achieve zinc oxide (ZnO) films for Cu2ZnSnS4 (CZTS) solar cells window layer at controlled annealing conditions as a potential approach to address elemental inter-diffusion in CZTS solar cells. This involved rapid thermal annealing (RTA) of room-temperature oxygenated DC sputtered zinc thin films in an ambient of nitrogen gas at different temperatures. Structural, morphological, optical, and electrical properties of these films were determined by X-ray diffractometer, Scanning Electron Microscopy, Ultraviolet-visible-near infrared spectrophotometer, and Hall Effect measurement, respectively. ZnO phases were observed after annealing the films over 150 °C. The films’ grains sizes improved with increasing RTA temperature. An exponential decrease in these films’ resistivity was observed with increasing RTA temperature attaining the lowest value at 300 °C. The bandgap and average solar transmittance of the films increased with increasing RTA temperature achieving values that are potential for applications in CZTS solar cells window layer at RTA temperatures beyond 200 °C.
 Keywords: Sputtering; Rapid thermal annealing; Zinc oxide; Structural; Opt-electrical

Optical studies of InAs/GaAs quantum dot stacks for photovoltaic applications

We have investigated the effect of post growth rapid thermal annealing on self-assembled InAs/GaAs mul tilayer QDs (MQD) overgrown with a combination barrier of InAlGaAs and GaAs for their possible use in photovoltaic device application. The samples were characterized by transmission electron microscopy and photoluminescence measurements. We noticed a thermally induced material interdiffusion between the QDs and the wetting layer in the MQD sample up to a certain annealing temperature. The QD heterostructure exhibited a thermal stability in the emission peak wavelength on annealing up to 700 ◦C . A phenomenological model has been proposed for this stability of the emission peak. The model considers the effect of the strain field, propagating from the underlying QD layer to the upper layers of the multilayer QD and the effect of indium atom gradient in the combination barrier layer due to the presence of a quaternary InAlGaAs layer.

1 eV GaAsSbN–based solar cells for efficient multi-junction design: Enhanced solar cell performance upon annealing

In this work, we demonstrate the beneficial effect of post-growth rapid thermal annealing (RTA) on the performance of ~1 eV GaAsSbN-based solar cells. Different configurations of the dilute nitride material are studied: a bulk quaternary GaAsSbN layer and type-II GaAsSb/GaAsN superlattices (SL) with different period thickness. The RTA treatment leads in both types of structures to an enhanced external quantum efficiency (EQE) and reduced values of the dark saturation current and series resistance. The origin of these improvements is attributed to reduced densities of N and Sb-rich clusters and point defects. Remarkably, all solar cell parameters are substantially improved, this being particularly significant for the short circuit current density (JSC) and power conversion efficiency (PCE), the latter with a relative enhancement as high as 500%. The large increment of JSC is an important step towards current–matching in multi–junction solar cells containing GaAsSbN structures.

Effect of Rapid Thermal Annealing on the Emission Properties in InGaAsSb/AlGaAsSb Multiple Quantum Wells

An effect of rapid thermal annealing (RTA) on emission properties of InGaAsSb/AlGaAsSb multiple quantum wells (MQWs) grown by molecular‐beam epitaxy is systematically investigated by photoluminescence (PL) spectra. The emission from free‐exciton and localized carriers is confirmed in as‐grown InGaAsSb/AlGaAsSb MQWs using temperature and excitation power‐dependent PL spectra. The results of RTA for different times at a fixed temperature of 350 °C are analyzed. The PL intensity of InGaAsSb/AlGaAsSb MQWs is increased after an RTA process, and the peak position is slightly blueshifted at 300 K. Low‐temperature PL spectra show improved emission of free‐exciton and deteriorated localized carriers recombination at an annealing time of 60 s. Double crystal X‐ray diffraction (DCXRD) measurements are also carried out to study the crystalline quality before and after annealing. These results indicate that a suitable RTA treatment is effective in reducing the densities of nonradiative recombination centers, which implies an improved optical property and crystalline quality of quantum well structures. This study provides valuable understanding of recombination processes and improvement of optical properties by RTA treatment in InGaAsSb/AlGaAsSb MQWs.

Rapid thermal oxidation of nano silver film for solar cell fabrication

In this paper, the nano Silver dioxides films have been deposited using the reactive pulsed laser deposition method (RPLD) using the tattoo removal Q-swithing Nd-Yag laser, at the value of the wavelength of 1064nm, pulseduration of 6 sec, and 800 mJ energy of laser have been applied for ablated an extra purity of the Silver target then deposited the nano siver oxide particles on the silicon substrates, synthesize and studying of the rapid thermal annealing (RTA) effects on the structural properties, the morphological properties, the Optical properties, the electrical properties and finally the solar cell properties for the prepared samples. Both X-ray diffraction and electron microscopy studies show that the structure of the film depends on the annealing teamperatures effects of the deposited film. The nano silver oxide is present in different crystalline stages, where the particle sizes have been increases with increasing heat treatment from 45nm to 75 nm. The analized Results of the optical aprove the improvements of the absorption lead to decreasing the reflection values compared with the surface of the silicon (crystalline Si), where the transparency for the range of larger than 300 nm and the values of the optical band gap of 2.12 eV. The synthesized results for the solar cell fabrications present a clear improvement in the solar cell quantum efficiency values in the case of silver nano oxide deposition and annealed with the high degree, where the value of the efficiency about of 4.22.

Effects of rapid thermal annealing as back contacts activation treatment on CdS/CdTe multi-contacted solar cells

Cd2SnO4/CdS/CdTe/CuxTe/Au structure solar cells were made in samples of 20 × 20 mm2. Multiple metallic back-contacts were deposited on each sample by thermal evaporation. A series of rapid thermal annealing treatments (RTA) were performed on the cells, controlling work pressure (Pw) and temperature (Ta), to activate the interface of CdTe-back contact. Several combinations of pressure (746 mbar ≤ Pw ≤ 1112 mbar) and temperature (180 °C ≤ Ta ≤ 260 °C) were studied. The best results were obtained for the lowest Pw, increasing the average efficiency from 6.9% to 9.8% as Ta increased. All photovoltaic parameters (VOC, JSC, FF, RS, and RSh) were enhanced with the RTA treatments along with the dispersion values. Once the thermal activation's optimal conditions were determined, the highest efficiency was 11.3% with an RTA single treatment. The improvement is attributed to the formation of Cu1·85Te phase. It is shown that this kind of thermal treatment on CuxTe/Au back-contact of the cells can be employed to obtain higher area solar cells.

Влияние быстрого термического отжига на распределение атомов азота в GaAsN/GaAs

The article investigates the effect of rapid thermal annealing of ternary GaAs1-xNx/GaAs solid solutions on the distribution of nitrogen atoms in the crystal lattice. The samples are studied by photoluminescence spectroscopy and high-resolution X-ray diffractometry. Due to the size and electronegativity mismatch of nitrogen and arsenic atoms, nitrogen is incorporated unevenly into the GaAs crystal lattice. Options of the nitrogen atoms arrangement in the GaAs crystal lattice before and after rapid thermal annealing are shown.

Preparation of optically transparent and conducting radio-frequency sputtered indium tin oxide ultrathin films

Highly conducting and optically transparent indium tin oxide (ITO) ultrathin films (thickness < 100 nm) are needed in order to improve the performance of optoelectronic devices, especially for plasmonic enhanced photovoltaic devices. ITO thin films (thickness ~ 60 nm) are deposited on glass substrates at room temperature by radio-frequency magnetron sputtering with a power of 200 W under argon atmosphere followed by rapid thermal annealing for 1 min at various temperatures in nitrogen environment. The effect of rapid thermal annealing on the physical and chemical changes of the ITO thin films is explored and co-related the changes with optoelectronic properties of the films as well. As-deposited thin films after rapid thermal annealing at 600°C display significant changes in the microstructure with occurrence of crystallites (average crystallite size ~ 11.9 nm), average optical transmittance (~ 88.2%) in the visible region, and electrical resistivity as low as 1.09 × 10−4 Ω-cm with high figure of merit of 2.27 × 10−2 Ω−1 — indicating their suitability as transparent conducting anode for the relevant electronics.

Research on the photoluminescence of spectral broadening by rapid thermal annealing on InAs/GaAs quantum dots

Photoluminescence (PL) test was conducted to investigate the effect of rapid thermal annealing (RTA) on the optical performance of self-assembled InAs/GaAs quantum dots (QDs) at the temperatures of 16 and 300 K. It was found that after RTA treatment, the PL spectrum of the QDs sample had a large blue-shift and significantly broadened at 300 K. Compared with the as-grown InAs QDs sample, the PL spectral width has increased by 44.68 meV in the InAs QDs sample RTA-treated at 800 °C. The excitation power-dependent PL measurements showed that the broadening of the PL peaks of the RTA-treated InAs QDs should be related to the emission of the ground state (GS) of different-sized InAs QDs, the InAs wetting layer (WL) and the In0.15Ga0.85As strain reduction layer (SRL) in the epitaxial InAs/GaAs layers.

Effects of rapid thermal annealing on aluminum nitride waveguides

The effects of rapid thermal annealing (RTA) on aluminum nitride (AlN) waveguides were investigated. For the AlN prepared by the sputtering, high temperature annealing for too long time may deteriorate the device performance, while a 6-7 times RTA with a 60 s annealing at a temperature of 800 °C would result in a lowest waveguide loss of about 0.76 dB/cm. After annealing, self-pumped four-wave mixing was performed on an 800-nm-wide, 5.8-mm-long waveguide. With a pump beam launched into the waveguide, signal and idler sidebands can be generated, which shows that RTA assisted sputtering grown AlN can have a potential to be applied for optical frequency comb generation.

Fabrication and Characterization of Oxygenated AlN/4H-SiC Heterojunction Diodes.

The effects of rapid thermal annealing (RTA) on Schottky barrier diodes (SBDs) made from oxygenated aluminum nitride (AlN) thin films deposited on a silicon carbide (SiC) substrate using radio frequency sputtering were investigated. The annealed SBD devices exhibited a 10x increase in the on/off current ratio vs. non-annealed devices for measurement temperatures ranging from 300 K to 450 K. The ideality factor, derived from the current density–voltage (J-V) characterization, increased by a factor of ~2.2 after annealing, whereas the barrier height decreased from ~0.91 to ~0.68 eV. Additionally, Auger electron spectroscopy indicated decreased concentrations of atomic oxygen in the AlN thin film, from ~36% before, to ~24% after annealing. This may have contributed to the reduced barrier height and improved on/off ratio in the annealed AlN/SiC diodes.

Effect of rapid thermal annealing on damage of silicon matrix implanted by low-energy rhenium ions

The structural, electronic, and magnetic properties of low-energy rhenium implanted c-Si are examined for the first time. The damage created by rhenium ions and the following partial reconstruction of the silicon host matrix after rapid thermal annealing (RTA) are investigated as a function of the fluence. Rutherford backscattering spectrometry (RBS) results reveal that the implanted ions are located in the near-surface region with the distribution maximum at about 23 nm below the surface. The analysis of rhenium-depth distribution using the McChasy code shows that the implanted Re-ions are located in the interstitial lattice positions. The RTA leads to a partial recovery of the silicon crystal structure. According to the RBS results, the formed inclusions are not coherent with the silicon host matrix causing an increase of the lattice distortion. Analysis of channeled RBS/c spectra carried out by the McChasy code revealed different levels of bent channels in damaged regions suggesting bimodal distribution of inclusions in the silicon. Studies of high-resolution X-ray photoelectron spectroscopy (XPS) conducted after the RTA showed the shift of Re 4f7/2 binding energy (BE) by +0.68 and + 0.85 eV with respect to metallic rhenium for the samples with lower/higher fluencies, respectively. Complex XPS, density functional theory (DFT) simulations, and transmission electron microscopy (TEM) data analysis allowed us to conclude that the near-surface layer of the sample (∼10 nm) consists of nanoinclusions with cubic and/or hexagonal ReSi. In the middle area of the samples, much larger nanoinclusions (>10/20 nm for higher/lower fluencies, respectively) containing pure metallic rhenium inside are formed. The RTA increases the magnetic moment of the sample with the lower dose nearly 20-fold, whereas in the sample with the higher dose a 3-fold increment is observed only. The magnetic response of the examined systems after the RTA indicates a presence of magnetic interactions between the nanoinclusions resulting in the system exhibiting super-spin glass or super-ferromagnetism.