Function Of Post-deposition Annealing Temperature Research Articles

Effects of post-deposition annealing in oxygen ambient of RF magnetron sputtered Ga<SUB align="right">2O<SUB align="right">3 thin film

An investigation on the radio frequency magnetron sputtered gallium oxide (Ga2O3) thin films on Si (100) subjected to different post-deposition annealing temperatures of 400, 600, 800, and 1000°C for 60 min in oxygen ambient was carried out in this work. Grazing incidence X-ray diffraction (GIXRD) revealed the formation of polycrystalline Ga2O3 thin films with an improvement in crystalline quality as the post-deposition annealing temperature was enhanced from 400 to 1000°C. The improvement in crystalline quality of Ga2O3 thin films was related to a reduction in the concentration of oxygen vacancies, wherein energy-dispersive X-ray spectroscopy has revealed an increment in atomic percentage of oxygen from 62.63 to 66.66 as a function of post-deposition annealing temperature. The changes from compressive to tensile microstrain induced on the investigated Ga2O3 thin films during post-deposition annealing at/beyond 800°C have revealed the occupancy of more oxygen vacancies. Thus, an increment in values of direct and indirect bandgap of Ga2O3 thin films was attained with respect to post-deposition annealing temperature. Nonetheless, it was perceived that the formation of interfacial layer was exaggerated at 1000°C, wherein an exceptionally low leakage current density has been demonstrated by Ga2O3 thin films annealed at 1000°C.

Multichromic Vanadium Pentoxide Thin Films Through Ultrasonic Spray Deposition

Vanadium pentoxide (V2O5) is a highly promising material for optoelectronic applications due to its wide optical band gap, significant thermal/chemical stability, and intriguing multichromic properties. Nonetheless, the production of uniform and crack-free V2O5 thin films over large areas via conventional deposition methods remain to be a challenge. In this work, we demonstrate deposition of microscopically uniform, large area (15 cm × 15 cm), nanocrystalline and multichromic V2O5 thin films onto fluorine-doped tin oxide (FTO) coated glass substrates via ultrasonic spray deposition (USD) method. Thin-film formation behavior, microstructural and optoelectronic properties of the deposited films were investigated as a function of post-deposition annealing temperature. Electrochromic performance of the fabricated films up to an area of 15 cm × 15 cm was monitored using cyclic voltammetry (CV), where 3 different coloration states of V2O5 were observed under different applied potentials. Electrochromic devices fabricated with the deposited V2O5 thin films were found to be stable up to 1000 cycles. Results presented herein provide a new roadmap for the large area deposition of V2O5 through USD method, which can be readily extended to a vast number of other functional metal oxide systems.

High Quality Magnetic Oxide Thin Films Prepared via Aqueous Solution Processing

Recent progress in multiferroic materials and spintronic devices has renewed interest in metal oxide ferromagnetic and ferrimagnetic materials. Here, we report the preparation of thin films of nanocrystalline ferrimagnetic CoFe2O4 (CFO) using an environmentally benign aqueous solution processing route. The evolution of the structural, optical, and magnetic properties as a function of postdeposition annealing temperature is reported. For the highest annealing temperature (800 °C), the remanence, coercivity, and resistivity values are comparable with those of films fabricated by epitaxial growth methods and exceed the quality of CFO nanocrystals prepared by other wet-chemical syntheses. In addition to the ability to make high quality ferrite films, the aqueous solution processing strategy offers great flexibility for tuning film properties by incorporating or substituting additional transition metal ions.

Correlating optical damage threshold with intrinsic defect populations in fused silica as a function of heat treatment temperature

Chemical vapour deposition (CVD) is used for the production of fused silica optics in high-power laser applications. However, relatively little is known about the ultraviolet laser damage threshold of CVD films and how they relate to intrinsic defects produced during deposition. We present here a study relating structural and electronic defects in CVD films to 355 nm pulsed-laser damage threshold as a function of post-deposition annealing temperature (THT). Plasma-enhanced CVD based on SiH4/N2O under oxygen-rich conditions was used to deposit 1.5, 3.1 and 6.4 µm thick films on etched SiO2 substrates. Rapid annealing was performed using a scanned CO2 laser beam up to THT ∼ 2100 K. The films were then characterized using x-ray photoemission spectroscopy, Fourier transform infrared spectroscopy (FTIR) and photoluminescence spectroscopy. A gradual transition in the damage threshold of annealed films was observed for THT values up to 1600 K, correlating with a decrease in non-bridging silanol and oxygen deficient centres. An additional sharp transition in damage threshold also occurs at ∼1850 K indicating substrate annealing. Based on our results, a mechanism for damage-related defect annealing is proposed, and the potential of using high-THT CVD SiO2 to mitigate optical damage is also discussed.

Defect states in epitaxial HfO2 films induced by atomic transport from n-GaAs (100) substrate

We investigated the chemical states and nature of the defect states below the conduction band edge of HfO2 films grown on GaAs (100) substrates using high-resolution x-ray photoelectron spectroscopy (HRXPS), x-ray absorption spectroscopy (XAS), and density functional theory calculations. O K1-edge absorption spectra of the HfO2/GaAs film revealed two distinct conduction band edge defect states, located at 1.6 ± 0.2 eV and 3.0 ± 0.2 eV below the conduction band edge in HfO2. The combined XAS and HRXPS results as a function of post-deposition annealing temperature indicated that the changes in defect states below the conduction band edge of HfO2 were correlated with the extent of interfacial chemical reactions between the HfO2 film and the GaAs substrate. Spectroscopic and theoretical results revealed that the two conduction band defect states are caused by (i) diffused Ga–O states, Hf3+ states, and (ii) an O divacancy related to the As–O states, respectively.

Effects of N2O Postdeposition Annealing on Metal-Organic Decomposed CeO2 Gate Oxide Spin-Coated on GaN Substrate

Effects of postdeposition annealing (PDA) in N2O ambient on metal-organic decomposed CeO2 films deposited on GaN substrate had been reported. The utilization of N2O gas during PDA had successfully suppressed the decomposition of GaN as revealed by x-ray diffraction (XRD). XRD had detected the presence of CeO2 and α-Ce2O3 phases, wherein the phase transformation of CeO2 to α-Ce2O3 led to the formation of β-Ga2O3 interfacial layer (IL). Formation of IL comprising of Ga–O and Ga–O–N compounds in CeO2/GaN system was verified by dark-field scanning transmission electron microscope image and energy dispersive x-ray line profile, respectively. The metal–oxide–semiconductor characteristics of CeO2/GaN structure showed a change of negative to positive effective oxide charge (Qeff) and increasing interface-trap density (Dit) as a function of PDA temperature. The highest oxide breakdown field demonstrated by 1000°C-annealed sample was correlated with Qeff and Dit. A detailed explanation on this correlation as well as current transport mechanism in these oxides has been presented.

Changes in Electronic Structure of LaxAlyO Films as a Function of Postdeposition Annealing Temperature

Amorphous films, containing 100, 50, and 30% La, were deposited by atomic layer deposition (ALD) on ultrathin films . Changes in the depth profile, as a function of composition, and structure were examined by medium energy ion scattering and transmission electron microscopy. The electronic structure of the films was investigated by X-ray photoelectron spectroscopy as a function of La concentration and postdeposition annealing temperature. In the case of a pure film without , the at the interfacial layer had been converted to and La silicate during the ALD process. However, in case of a film with , interfacial reactions were significantly suppressed. In particular, silicate formation in the films gradually increased with the increasing annealing temperature, while that in films incorporated was suppressed up to an annealing temperature of .

Reversible and irreversible reactions of three oxygen precursors on InAs(0 0 1)-(4 × 2)/ c(8 × 2)

The substrate reactions of three common oxygen sources for gate oxide deposition on the group III rich InAs(0 0 1)-(4 × 2)/ c(8 × 2) surface are compared: water, hydrogen peroxide (HOOH), and isopropyl alcohol (IPA). Scanning tunneling microscopy reveals that surface atom displacement occurs in all cases, but via different mechanisms for each oxygen precursor. The reactions are examined as a function of post-deposition annealing temperature. Water reaction shows displacement of surface As atoms, but it does not fully oxidize the As; the reaction is reversed by high temperature (450 °C) annealing. Exposure to IPA and subsequent low-temperature annealing (100 °C) show the preferential reaction on the row features of InAs(0 0 1)-(4 × 2)/ c(8 × 2), but higher temperature anneals result in permanent surface atom displacement/etching. Etching of the substrate is observed with HOOH exposure for all annealing temperatures. While nearly all oxidation reactions on group IV semiconductors are irreversible, the group III rich surface of InAs(0 0 1) shows that oxidation displacement reactions can be reversible at low temperature, thereby providing a mechanism of self-healing during oxidation reactions.

Structural and Electrical Characterization of Si-Implanted TiN as a Diffusion Barrier for Cu Metallization

AbstractThe feasibility of Si-implanted TiN as a diffusion barrier between Cu and Si was investigated. Barrier effectiveness was evaluated via reverse leakage current of Cu/TixSiyNz/Si diodes as a function of post-deposition annealing temperature and time, and was found to depend heavily on the film composition and microstructure. TiN implanted with Si28, l0keV, 5xl016ions/cm2 formed an amorphous ternary TixSiyNz layer whose performance as a barrier to Cu diffusion exceeded that of unimplanted, polycrystalline TiN. Results from current-voltage, transmission electron microscopy (TEM), and Auger depth profiling measurements will be presented. The relationship between Si-implantation dose, TixSiyNz structure and reverse leakage current of Cu/TixSiyNz/Si diodes will be discussed, along with implications as to the suitability of these structures in Cu metallization.