Mass-separated 56Fe+ ions were implanted into Si(100) at 350 °C using three different energies and doses of 140 keV (1.32×1017 cm−2), 80 keV (6.20×1016 cm−2), and 50 keV (3.56×1016 cm−2). Their optical properties were investigated as a function of subsequent annealing temperature and its duration time. X-ray diffraction analysis revealed that polycrystalline semiconducting β-FeSi2 layers are formed in the as-implanted and annealed samples. From Rutherford backscattering spectrometry analysis, the formation of β-FeSi2 up to the surface was confirmed, and the average thickness and composition of the layers at peak concentration were estimated to be 70–75 nm and Fe:Si=1:2.0–2.2, respectively. The types of optical transition and the inverse logarithmic slope (E0) of the Urbach tail were investigated using room temperature optical absorption measurements. All the synthesized β-FeSi2 layers exhibited a direct transition with direct band-gap energies (Egdir) of 0.802–0.869 eV and with high optical absorption coefficients extending to 105 cm−1 at photon energy above 1.0 eV. The E0 value characteristic of the Urbach tail was observed to decrease from 260 to 100 meV with elevating annealing temperature. Some of the materials having E0<160 meV showed two strong photoluminescence (PL) emissions peaked at 0.805–0.807 eV (No. 1) and 0.840–0.843 eV (No. 2) at 2 K, whereas those with E0≳250 meV exhibited only weak emissions. From the results of the temperature- and excitation power-dependent PL measurements, emissions Nos. 1 and 2 were attributed to the trap-related recombinations related to β-FeSi2, with thermal activation (quenching) energies of 54.7 and 46.7 meV, respectively.
Porous low-k materials are required in the construction of 45 nm node large-scale integrated devices. However, the extremely low Young's modulus values of these materials results in a high number of previously unreported defects. A porous low-k film stacked with a dense low-k film showed pronounced cracking in its Cu wiring, which was concentrated in isolated lines 0.18 m in width and was accelerated with longer chemical-mechanical polishing ͑CMP͒ times. Denser lines showed less cracking and the single structure of a dense low-k film showed no cracking. We hypothesized that this cracking might be categorized as stress corrosion cracking ͑SCC͒. Accordingly, we investigated the relation between stress and corrosion in certain kinds of slurry. We have also researched the effects on corrosion of temperature and various metals. In all of the slurry that we tested, tensile stress increased corrosion current in Cu samples. Furthermore, both finite element method analysis of stress during CMP and measurements of friction on the Cu/low-k surface by scanning probe microscopy indicated concentration of stress on low-k materials, especially at the edges of isolated wiring. Thus, we concluded that stress enhances corrosion during CMP and that there was a high possibility of SCC.
The relationship between microgram structures and electrical characteristics of sputtered indium tin oxide (ITO) films was investigated. Micrograin structures were observed by a high resolution scanning electron microscope. Electrical characteristics were evaluated by four point probe resistance measurement and Hall effect measurement. Low resistivity IT0 fihns had domain structures. One domain consisted of many sputter grains having the same orientation. The resistivity decreased with increasing domain size. The domain boundary might cause scattering for conduction electrons. Therefore, larger domain IT0 films had a higher Hall mobility. The minimum resistivity was 1.8X low4 n cm, deposited at a sputtering voltage of -250 V and a 250 "C deposition temperature. The electron conduction mechanism in domain structured IT0 films was taken into consideration.
The influence of postdeposition annealing on sputtered indium tin oxide (ITO) film characteristics were investigated. The annealing experiments were carried out in air or vacuum atmosphere. Both air and vacuum annealing decreased the resistivity up to heat treatment of 200° C. Over 300° C treatment, air annealing increased resistivity whereas vacuum annealing decreased it. It was clarified that the resistivity depended on the carrier concentration. The lowest resistivity attained was 1.3×10-4 Ω·cm, with film deposited on a 250° C heated substrate and annealed in vacuum atmosphere at 300° C. Transmittance was improved in both air and vacuum annealing. In air and vacuum annealing, crystallinity improved with increasing annealing temperature. The surface topography showed no changes with air or vacuum annealing.
We prepared othorhombic β-FeSi2 thin-films on Si(111) substrates by a pulsed laser deposition method (PLD) and studied the relationship between bandgap energy and composition ratio by themal annealing of β-FeSi2 thin-films on Si substrate. When the substrate temperature was 500·°C, β-FeSi2 thin-films were grown on Si(111) substrates. The sample prepared on Si(111) substrate was a monocrystalline structure since only (220) or (202) signals of β-FeSi2 were observed. A large amount of defects existed in the thin film. These defects were reduced by using high temperature and long time annealing. Heat treatment of 20 hours or more time was effective for reducing diffect. The iron diffusion of β-FeSi2/Si interface was observed by RBS spectra. Composition ratio of the prepared β-FeSi2 was Fe:Si=30:70. As-deposition β-FeSi2 was Si-rich. The p-n diode characteristics of these heterostructure diodes were investigated by C-V measurements. β-FeSi2/Si interface prepared by 400· °C was an ideal one-side step junction. The surface roughness was decreased by annealing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.