Effect Of Post-deposition Annealing Research Articles

Effects of Postdeposition Annealing on the Electrical Properties of Cu2O/4H–SiC PiN Diodes

Copper oxide (Cu2O) is a promising p‐type material owing to its high absorption coefficient, suitable bandgap width, chemical stability, nontoxicity, and abundance. In this study, the effect of postdeposition annealing (PDA) on the electrical properties of Cu2O thin films deposited on silicon carbide (SiC) substrates is investigated. The films are subjected to PDA using radio‐frequency sputtering at various temperatures in air. During PDA, the Cu2O films are maintained at <300 °C and transitioned to cupric oxide (CuO) at 400 °C. The as‐deposited Cu2O film exhibits a low oxidation peak (Cu2+), whereas the phase‐transformed CuO films exhibit a higher binding energy with the emergence of satellite peaks. The rectification ratios of the Cu2O device annealed at 300 °C and CuO device annealed at 400 °C are determined as 2.02 × 107 and 1.01 × 105, respectively, denoting the substantial enhancement of approximately 55.04 for the Cu2O/SiC device and degradation of approximately 0.28 for the CuO/SiC device relative to their non‐annealed counterparts. Therefore, in this study, the significant improvement in the performance of Cu2O thin films with the meticulous deposition control of potential p‐type materials, such as Cu2O and CuO, for high‐throughput and low‐cost electronic applications is demonstrated.

Effect and Regulation Mechanism of Post-deposition Annealing on the Ferroelectric Properties of AlScN Thin Films.

Integrating ferroelectric AlScN with III-N semiconductors to enhance the performance and tunability of nitride devices requires high-quality AlScN films. This work focuses on the effect and regulation mechanism of post-annealing in pure N2 on the crystal quality and ferroelectric properties of AlScN films. It is found that the crystal quality improves with increasing annealing temperatures. Remarkably, the leakage current of AlScN films caused by grain boundaries could be reduced by four orders of magnitude after annealing at 400 °C. The crystal growth dynamics simulations and band structure calculations indicate that the energy supplied by the temperature facilitates the evolution of abnormally oriented grains to have a better c-axis orientation, resulting in the defect states at the Fermi-level disappearing, which is mainly the reason for the leakage current decrease. More interestingly, the reduction of leakage current leads to the previously leaking region exhibiting ferroelectric properties, which is of great significance to improve the ferroelectricity of AlScN and ensure the uniformity of devices. Furthermore, annealing enhances the tensile strain on the film, which flattens the energy landscape of ferroelectric switching and reduces the coercive field. However, the risk of incorporation of oxygen will also be increased if the annealing temperatures are higher than 400 °C, which will not only reduce the relative displacement of metal atoms and nitrogen atoms in AlScN but also enhance the ferroelectric depolarization field, leading to the remnant polarization decreasing dramatically. These discoveries facilitate a deeper understanding of the influencing mechanism on the ferroelectric properties of AlScN films and provide a direction for obtaining high-quality AlScN.

Plasma assisted pulsed laser deposition of WO3 films for thermochromism

Tungsten trioxide (WO3) is one of the extensively investigated transition metal oxides. Its excellent chromogenic properties make WO3 promising for a variety of scientific and technological applications. We report a new method for reactively depositing WO3 films by plasma assisted pulsed laser deposition that combines electron cyclotron resonance microwave discharge and pulsed laser ablation. The plasma formed during film deposition was spectroscopically characterized by optical emission measurement, revealing that the plasma contains high density of reactive gaseous oxygen and tungsten species which are essential for efficiently synthesizing WOx precursors and depositing WO3 films. The structure of the deposited films and the effect of post-deposition thermal annealing on the film structure were characterized by X-ray diffraction and Raman spectroscopy. The as-deposited WO3 film appears amorphous in nature. Annealing resulted in the growth of crystalline grains and the improvement in the crystallinity of monoclinic WO3. Optical properties of the prepared WO3 films were studied by measuring ultraviolet–visible–near infrared transmission spectra. With the increase of annealing temperature, the WO3 films show a continuous change in color, decline in transmittance, red shift in absorption edge, and narrowing in band gap, clearly manifesting the thermochromic features of the deposited WO3 films.

Impact of post-deposition annealing on the electronic properties of Al2O3/GaN interface by first-principles study

The electronic properties of Al2O3/GaN interface are investigated by first-principles calculations to explore the effects of post-deposition annealing (PDA) in O2 or N2 ambient. It is found that for the initial Al2O3/GaN interface without post-annealing, there are traps with a wide energy range in the GaN band gap, mainly caused by dangling bonds (DBs) of Ga, Al, and N atoms. However, with proper PDA in O2 ambient, the trap states induced by Al DBs completely merge into GaN conduction band, while the trap states induced by Ga DBs and N DBs completely merge into GaN valence band. Therefore, the interface shows a cleaner band structure. Nevertheless, excessive interface O content can lead to trap states around the valence band maximum induced by N DBs and O DBs. For PDA in N2 ambient, the trap states induced by Al DBs and Ga DBs can be completely suppressed under appropriate interface N content. Unfortunately, deep and shallow traps caused by N DBs can be introduced in the GaN band gap. This study systematically reveals the physical mechanism by which PDA in O2 ambient compared to N2 can significantly reduce the interface state density and improve threshold voltage stability of the device.

Effect of high temperature annealing on cryogenic transport properties of silicon MOSFETs with a thin SiO2/HfO2 stacked dielectric

Quantum computing is expected to break the computing power bottleneck with the help of quantum superposition and quantum entanglement. In order to fabricate fault-tolerant quantum computers for encoding quantum information, it is important to improve the cryogenic mobility of silicon-based metal oxide semiconductor field effect transistors (MOSFETs) with a thin gate dielectric layer as much as possible. Based on a thin SiO2/HfO2 stacked dielectric, we investigate the effect of post-deposition annealing (PDA) temperature on the MOSFET cryogenic transport properties. The results show that silicon atoms will diffuse into the HfO2 to form silicates during PDA, leading to the HfO2 dielectric constant decrease. As the PDA temperature increases, the proportion of monoclinic hafnium oxide decreases and the tetragonal phase increases gradually. The oxygen vacancy content increases gradually, resulting in fixed charge density increases and the mobility decreases. The contribution of the forming gas annealing (FGA) to the mobility enhancement is clarified and the HfO2 recrystallization process is revealed from the perspective of long-time annealing. Finally, the mobility peak of silicon MOSFETs with thin SiO2/HfO2 dielectrics is enhanced to 1387 cm2(V·s)−1 at 1.6 K, which provides a technical pathway for the development of silicon-based quantum computation.

Plasma-enhanced atomic layer deposition of nickel and nickel oxide on silicon for photoelectrochemical applications

The production of hydrogen fuel through sunlight-driven water splitting has the potential to harness and store large quantities of solar energy in a clean and scalable chemical state, suitable for later use in a range of energy applications. Silicon (Si) possesses many of the required properties to be used effectively as a photoelectrochemical (PEC) water-splitting photoanode. However, its sensitivity to corrosion during the oxygen evolution reaction limits its performance in photoanode applications, thus requiring additional overlayer materials to protect the underlying Si substrate. Nickel oxide (NiO) is one material that acts as an effective protective layer, being transparent, suitably conductive and stable. In this work, we present NiO deposition via state-of-the-art atomic layer deposition and photoemission studies to grow and characterize NiO and Ni–metal protective films. Early-stage nucleation of deposited thin films is illustrated along with the effects of post-deposition annealing and argon milling on depth profile information. Previous reports on the effects of slow argon milling are explored and counter arguments are proposed. Protective films are subjected to PEC testing, which shows enhancement of stability and photocurrent output as a result of the deposited films and plasma annealing on these thin films.

Post-deposition annealing effects on microstructure, mechanical and tribological properties of AlCrN films

The post-deposition annealing of AlCrN films was conducted in an atmospheric environment for 2 h, with annealing temperatures ranging from 25 to 1000 °C. The microstructure, mechanical, and tribological properties were systematically investigated as a function of the annealing temperature. The results show that the AlN phase in the film began to oxidize at 600 °C, resulting in deterioration of the film's toughness and resistance to plastic deformation. Subsequently, the wear resistance also deteriorated, with the wear rate being nearly 16 times that of the as-deposited film. At 800 °C, the AlN obviously underwent oxidization to form Al2O3. The high temperature annealing promoted the coalescence of Cr on the film surface and caused a reaction with the Al2O3 to form a replacement solid solution of Cr–O–Al, thereby improving the mechanical properties of the annealed films. At the same time, the tribological properties of the films were not significantly deteriorated by annealing at temperatures other than 600 °C, similar to those of the films without any annealing treatment.

Exploring thermally stable metal-oxide/SiO2 stack for metal oxide semiconductor memory and demonstration of pulse controlled linear response

We fabricated Al2O3/SiO2 stack structures with atomically thin Ti oxide layers at the interfaces using atomic layer deposition and investigated the capacitance–voltage (C–V) hysteresis of the metal-oxide-semiconductor (MOS) capacitors. We studied the effect of post-deposition annealing in the temperature range of 150 °C−500 °C on the C–V hysteresis and found that the Al2O3/SiO2-based stacks are thermally stable compared to ZrO2/SiO2- and HfO2/SiO2-based stacks. Using Al2O3/SiO2-based stacks, we investigated the impact of oxide layer thickness and gate electrode materials and studied pulse-induced current changes in MOS field-effect transistors.

Effects of post-deposition annealing temperature and atmosphere on interface properties in ALD Al2O3/plasma oxidation GeO x /(111) and (100) n-Ge MOS structures

In this work, the effects of post-deposition annealing (PDA) on Al2O3/GeO x /(111) and (100) n-Ge structures are experimentally studied with changing annealing temperatures from 300 °C to 650 °C in a vacuum, N2 and O2 atmosphere in order to clarify the stability of the MOS interface properties under high-temperature annealing. A decrease in D it and an increase in the oxide capacitance with increasing PDA temperature is observed up to 500 ∼ 600 °C, depending on the annealing atmosphere and surface orientation. The minimum D it of ∼3 × 1011 eV−1cm−2 is achieved for (111) Ge after PDA at 550 °C and 600 °C in N2/O2 or vacuum. This trend is similar to the (100) MOS interfaces and a similar amount of minimum D it is obtained. These results suggest that the present Al2O3/GeO x /Ge interfaces are suitable for the formation of the Ge-On-insulator (GOI) back interfaces by the wafer bonding process in the Smart-cut, where high-temperature annealing is indispensable.

Reduction of interface and oxide traps in SiO2/GaN MOS structures by oxygen and forming gas annealing

The effect of post-deposition annealing on the electrical characteristics of SiO2/GaN MOS devices was investigated. While the key to the improvement was using oxygen annealing to form an interfacial GaO x layer and forming gas annealing to passivate the remaining defects, caution must be taken not to produce a fixed charge through reduction of the GaO x layer. By growing the GaO x layer with oxygen annealing at 800 °C and performing forming gas annealing at a low temperature of 200 °C, it became possible to suppress the reduction of GaO x and to reduce the interface traps, oxide traps, and fixed charge simultaneously.

Post-deposition annealing effects of copper oxide (Cu2O) thin film deposited using E-beam evaporation

Post-deposition annealing effects of copper oxide (Cu2O) thin film deposited using E-beam evaporation

The enhancement of NIR transparency due to annealing and Mg-doping in [formula omitted] thin films

The effect of post-deposition annealing on the structural and optical properties of CuCrO2 and Mg-doped CuCrO2 thin films is reported. The prepared films were annealed in Helium atmosphere at 300 °C. X-ray diffraction analysis revealed the decreased crystallinity and Raman studies clarify the decreased copper defects at interstitials sites with annealing. The NIR wavelength transparency increases and the maximum transmission of 72% was obtained for Mg-doped annealed film of 211 nm thickness.

Post-deposition annealing effect on the structural and electrical properties of ytterbium oxide as an alternative gate dielectric

The possibility of ytterbium(III) oxide, one of the rare earth oxides, to replace silicon dioxide used as the gate dielectric is discussed in this article. For such a replacement, it is primarily necessary to understand the physical and chemical characteristics of ytterbium(II) oxide as a candidate, such as bond structure, electronic structure, band offsets with Si, dielectric constant, interfacial states and defect behavior. The effects of structural and electrical features of ytterbium(III) oxide-based MOS capacitors on device performance are investigated. The electron beam physical vapor deposition (EBPVD) technique was used for the deposition of ytterbium(III) oxide thin films. The 122 nm thick Yb2O3 thin film was annealed at four different temperatures (200 °C, 400 °C, 600 °C, and 800 °C) in nitrogen environment. The crystallite size determined from the as-deposited sample as 15 nm is the lowest. As expected, crystallite sizes increased as a result of increasing annealing temperature. The presence of Yb2+ oxidation states increased in the region close to the interface or at the interface. The binding energies of the Yb 4d and O 1s spectra increased with increasing depth into the films. In the O 1s spectra, the organic bonds on the surface first decreased and then increased with increasing annealing temperature. Silicate formation at the interface was determined for the annealed samples. This affected the electrical performance of the capacitors. The calculated dielectric values range from 12.1 to 15.8. Interface level densities were found in the order of 1012 cm−2 and it did not exhibit frequency-dependent behavior. The calculated values for the effective charge densities varied between −24.19 × 1011–7.03 × 1011 cm−2. It has been determined that mostly negative charges are trapped more for different capacitors. Finally, Fermi energy level, dopant concentration, diffusion potential and barrier heights were calculated.

Effect of annealing on chemically deposited Cu2Se thin films

Cu2Se is a promising candidate in the field of photovoltaic and thermoelectric devices. The pristine Cu2Se thin films are observed to be unstable under ambient conditions. One of the instabilities reported in this material is the formation of dendritic structures on the surface. The present work discusses the effect of post-deposition annealing on the dendritic growth formation. The pristine Cu2Se films were vacuum annealed at 60 °C, 80 °C, 100 °C, 150 °C, and 180 °C and the properties of the samples were investigated. The XRD peak profile analysis was done to evaluate the microstructural parameters like crystallite size, microstrain, stress and energy density. The various techniques used for this study include Scherrer method, Modified Scherrer Method, Williamson-Hall Plots, and Size Strain Plot. The modified variants of W–H Plots were employed which included Uniform Deformation Model, Uniform Stress Deformation Model and Uniform Deformation Energy Density Model. In all these cases, the crystallite size was found to increase on annealing. This is attributed to the reduction in defects and dislocations due to annealing of the sample. Microstrain is also observed to increase with the increase in annealing temperature. The calculation of crystallite size and lattice strain using UDM model deviates more from other models. This may be due to the incompatibility of its basic assumption of isotropic strain in UDM model. The W–H plots also suggest the presence of tensile strain in the lattice. The Cu ions in pristine Cu2Se thin films are in a disordered state due to their high mobility and diffusion coefficient. These mobile Cu ions form the centres of anisotropy and participate in dendritic growth formation with suitable stimulants. With an increase in annealing temperature, these ions get ordered due to strain hardening which in turn stabilizes the Cu2Se structure. The minimum temperature required to resist dendritic growth formation was found to be 150 °C. Thus annealing of pristine sample is suggested as a simple but effective method towards stabilization of the matrix. During the annealing process in the temperature range 60 °C–180 °C, it is observed that the optical band gap decreased from 2.2 eV to 1.9 eV.

Effects of Postdeposition Annealing Ambience on NO2 Gas Sensing Performance in Si-Based FET-Type Gas Sensor

We investigate the effects of postdeposition annealing (PDA) ambience on the nitrogen dioxide (NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) gas sensing performance in the Si-based field-effect transistor (FET)-type gas sensor having an indium–gallium–zinc oxide (IGZO) as a sensing material. After the IGZO thin films are deposited, the sensors are postannealed in vacuum and atmospheric ambiences. The content of oxygen vacancy in IGZO films varies depending on the PDA ambience, which changes the electrical properties and NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas sensing performance of the sensors. The sensor postannealed in a vacuum ambience has more oxygen vacancy, which acts as an electrical donor, than that in an atmospheric ambience. Thus, the former has a larger coupling ratio and transconductance of the FET transducer. Also, the oxygen vacancy produces negatively charged oxygen species, increasing the response to NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Due to a larger response to NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas and low noise, the sensor postannealed in a vacuum shows excellent signal-to-noise ratio (SNR) and limit-of-detection performances.

The effect of post-deposition annealing on the chemical, structural and electrical properties of Al/ZrO2/La2O3/ZrO2/Al high-k nanolaminated MIM capacitors

The effect of post-deposition annealing on the chemical, structural and electrical properties of Al/ZrO2/La2O3/ZrO2/Al high-k nanolaminated MIM capacitors

Effects of annealing temperature on the mechanical, optical, and electrical properties of hydrogenated, nitrogen-doped diamond-like carbon films

We have deposited nitrogen-doped diamond-like carbon (N-DLC) films by plasma-enhanced chemical vapor deposition using H2 as a dilution gas and investigated the effects of post-deposition annealing in a vacuum on the film properties. It was found that the optical bandgap slightly increased after annealing at 235 °C, whereas it substantially decreased after annealing at 420 and 490 °C. At these temperatures, the critical load increased primarily due to a decrease in internal stress. Simultaneously, the amount of bound hydrogen in the films decreased, whereas sp2 C=C increased and its clustering was accelerated. On the other hand, both friction coefficient and specific wear rate became lowest at 347 °C. We found that the N-DLC/p-type silicon heterojunction annealed at 347 °C exhibited the highest rectification ratio. These results were discussed based on the structure and chemical bonding states of the annealed films.

Structure and optical properties of ZrxHf1-xO2 films deposited by pulsed laser co-ablation of Zr and Hf targets with the assistance of oxygen plasma

Group IVB metal oxides have demonstrated many potential applications in a variety fields owing to their excellent optical, mechanical, electrical, chemical and thermal properties. In this work, ternary oxides ZrxHf1-xO2 films with variable compositions were deposited by pulsed laser co-ablation of a Zr target and a Hf target in an oxygen plasma generated by electron cyclotron resonance microwave discharge of O2 gas. The oxygen plasma provided an environment containing a high concentration of reactive oxygen species for synthesizing oxides with the Zr and Hf species ablated from the Zr and Hf targets. The structure of the deposited films was characterized and the optical properties were evaluated together with the examination of the effects of post-deposition annealing on the structure and optical properties. The ternary ZrxHf1-xO2 films are much alike with binary ZrO2 and HfO2 films in structure and optical properties. They have a monoclinic structure and are highly transparent in a wide spectral region from mid-ultraviolet to mid-infrared. The ultraviolet absorption edge and optical band gap vary slightly with the pulse energies of the laser beams ablating the targets. Annealing in N2 resulted in the improvement in the film structure.

Hydrothermal growth of Sb2S3 thin films on molybdenum for solar cell applications: Effect of post-deposition annealing

The binary chalcogenide material antimony sulfide (Sb2S3) has attracted significant attention as a potential absorber material for photovoltaics (PVs) owing to its suitable bandgap of ~1.7 eV and other unique properties. However, only a few substrate-configured Sb2S3 thin-film solar cells (TFSCs) have been reported, and they demonstrated an extremely low power conversion efficiency (PCE, η < 2.5%) owing to the unfavorable (hk0) orientation of Sb2S3. In most studies, Sb2S3 absorber layers were grown through physical vapor deposition or high-vacuum methods. By contrast, we used a facile hydrothermal approach to deposit Sb2S3 thin films on molybdenum and investigated the effect of post-deposition annealing on the structure, orientation, and morphology of Sb2S3 thin films. Annealing at temperatures ranging from 0° to 350°C transformed the Sb2S3 thin films from nearly amorphous to polycrystalline with large, horizontally aligned plate-like grains. All the annealed Sb2S3 thin films were confirmed to have a preferred orientation along the (hk0) crystal direction. The fabricated substrate-configured TFSCs with SLG/Mo/Sb2S3/CdS/i-ZnO/Al-doped ZnO/Al configuration exhibited the highest PCE of ~1.0%. Further, over 95% of this initial efficiency was maintained after 90 days. We also addressed the underlying reasons for the low efficiency of Sb2S3 TFSCs to provide a pathway for improving the device performance in the future.

The effect of vacuum and air annealing on the structural, optical and photoluminescence properties of ZnS films

The deposition temperature and post-deposition heat treatment can be effectively used to fine tune the structure and composition of the films to obtain desired performance. In this paper, we have investigated the effect of elevated substrate temperature and post-deposition annealing (in air and vacuum) on the properties of ZnS films. Both the tools were found to produce considerable changes in the crystal structure of the films. The major impact was found to be an increase in crystallite size which effectively reduced the defects. Although a small amount of tensile stress was produced as a side-effect of heat treatment, the films remained structurally intact. The vacuum annealing was found to be far more productive than annealing in air. It produced nearly the same amount of improvement in the crystallite size, but with considerably less tensile stress. Furthermore, the bandgap of the films remained unaffected by vacuum annealing.