Abstract:In this letter we report the controlled growth and microstructural evolution of self-assembled nanocomposite multilayers that are induced by surface ion-impingement. The nanoscale structures together with chemical composition, especially at the growing front, have been investigated with high-resolution transmission electron microscopy. Concurrent ion impingement of growing films produces an amorphous capping layer 3 nm in thickness where spatially modulated phase separation is initiated. It is shown that the m… Show more
“…Chen et al reported that SD can be induced by ion-impingement during the deposition of amorphous TiC thin films by pulsed DC magnetron sputtering. They also found that the energy flux of impinging ions enhances the diffusion coefficient [15]. They have tentatively expressed ion-impingement-enhanced diffusion coefficient as [15,17]
10.1080/14686996.2018.1482520-F0006Figure 6.Phase separation in Mn ferrite films as a function of the growth temperature and magnetic field applied during the film growth.…”
Section: Resultsmentioning
confidence: 99%
“…They also found that the energy flux of impinging ions enhances the diffusion coefficient [15]. They have tentatively expressed ion-impingement-enhanced diffusion coefficient as [15,17]
10.1080/14686996.2018.1482520-F0006Figure 6.Phase separation in Mn ferrite films as a function of the growth temperature and magnetic field applied during the film growth. Red open circles, green crossed circles, and black crosses indicate that the phase separation was confirmed, initiated, and not observed, respectively.…”
Section: Resultsmentioning
confidence: 99%
“…This equation indicates that ion-impingement during thin film growth lowers the activation energy for up-hill diffusion and SD is consequently induced to bring about spontaneous phase separation [15,17,20]. It should be noted that the application of a magnetic field to the laser-ablated plume suppresses the recombination of electrons and ions.…”
Section: Resultsmentioning
confidence: 99%
“…Many researchers have paid more attention to self-organized one-step fabrication techniques to fabricate spinodally decomposed compounds or alloys. SD can be controlled or promoted by ion-impingement [15] or ion-bombardment [16] during thin film growth. On the other hand, we have developed a novel pulsed laser deposition (PLD) system by introducing an electromagnet in a PLD vacuum chamber.…”
In this study, we report about the occurrence of phase separation through spinodal decomposition (SD) in spinel manganese ferrite (Mn ferrite) thin films grown by Dynamic Aurora pulsed laser deposition. The driving force behind this SD in Mn ferrite films is considered to be an ion-impingement-enhanced diffusion that is induced by the application of magnetic field during film growth. The phase separation to Mn-rich and Fe-rich phases in Mn ferrite films is confirmed from the Bragg’s peak splitting and the appearance of the patterned checkerboard-like domain in the surface. In the cross-sectional microstructure analysis, the distribution of Mn and Fe-signals alternately changes along the lateral (x and y) directions, while it is almost homogeneous in the z-direction. The result suggests that columnar-type phase separation occurs by the up-hill diffusion only along the in-plane directions. The propagation of a quasi-sinusoidal compositional wave in the lateral directions is confirmed from spatially resolved chemical composition analysis, which strongly demonstrates the occurrence of phase separation via SD. It is also found that the composition of Mn-rich and Fe-rich phases in phase-separated Mn ferrite thin films deposited at higher growth temperature and in situ magnetic field does not depend on the corresponding average film composition.
“…Chen et al reported that SD can be induced by ion-impingement during the deposition of amorphous TiC thin films by pulsed DC magnetron sputtering. They also found that the energy flux of impinging ions enhances the diffusion coefficient [15]. They have tentatively expressed ion-impingement-enhanced diffusion coefficient as [15,17]
10.1080/14686996.2018.1482520-F0006Figure 6.Phase separation in Mn ferrite films as a function of the growth temperature and magnetic field applied during the film growth.…”
Section: Resultsmentioning
confidence: 99%
“…They also found that the energy flux of impinging ions enhances the diffusion coefficient [15]. They have tentatively expressed ion-impingement-enhanced diffusion coefficient as [15,17]
10.1080/14686996.2018.1482520-F0006Figure 6.Phase separation in Mn ferrite films as a function of the growth temperature and magnetic field applied during the film growth. Red open circles, green crossed circles, and black crosses indicate that the phase separation was confirmed, initiated, and not observed, respectively.…”
Section: Resultsmentioning
confidence: 99%
“…This equation indicates that ion-impingement during thin film growth lowers the activation energy for up-hill diffusion and SD is consequently induced to bring about spontaneous phase separation [15,17,20]. It should be noted that the application of a magnetic field to the laser-ablated plume suppresses the recombination of electrons and ions.…”
Section: Resultsmentioning
confidence: 99%
“…Many researchers have paid more attention to self-organized one-step fabrication techniques to fabricate spinodally decomposed compounds or alloys. SD can be controlled or promoted by ion-impingement [15] or ion-bombardment [16] during thin film growth. On the other hand, we have developed a novel pulsed laser deposition (PLD) system by introducing an electromagnet in a PLD vacuum chamber.…”
In this study, we report about the occurrence of phase separation through spinodal decomposition (SD) in spinel manganese ferrite (Mn ferrite) thin films grown by Dynamic Aurora pulsed laser deposition. The driving force behind this SD in Mn ferrite films is considered to be an ion-impingement-enhanced diffusion that is induced by the application of magnetic field during film growth. The phase separation to Mn-rich and Fe-rich phases in Mn ferrite films is confirmed from the Bragg’s peak splitting and the appearance of the patterned checkerboard-like domain in the surface. In the cross-sectional microstructure analysis, the distribution of Mn and Fe-signals alternately changes along the lateral (x and y) directions, while it is almost homogeneous in the z-direction. The result suggests that columnar-type phase separation occurs by the up-hill diffusion only along the in-plane directions. The propagation of a quasi-sinusoidal compositional wave in the lateral directions is confirmed from spatially resolved chemical composition analysis, which strongly demonstrates the occurrence of phase separation via SD. It is also found that the composition of Mn-rich and Fe-rich phases in phase-separated Mn ferrite thin films deposited at higher growth temperature and in situ magnetic field does not depend on the corresponding average film composition.
“…Spontaneous superlattice formation is also reported for metal alloy (Au-Ni) and carbide (TiC) thin films deposited under an ion-impingement (bombardment) atmosphere. 9,10 In their works, additional kinetic energy by ion-impingement is regarded as having a lower activation energy of up-hill diffusion, which is characteristic of spinodal decomposition. For oxides, few reports describe spontaneous superlattice formation during thin film deposition.…”
Periodically structured nanomaterials such as superlattices have a wide range of applications. Many electronic devices have been fabricated from these materials. The formation of spontaneous layer structures using epitaxial growth has also been reported for many compound semiconductors but for very few ceramics. We demonstrate that strontium titanate (Sr-Ti-O) thin films having an A-site excess composition in the perovskite structure deposited by pulsed laser deposition under a magnetic field show a spontaneously formed superlattice structure. The spontaneous superlattice formation mechanism has been proven to exhibit spinodal decomposition. Preparation of a part of the phase diagram for Sr-Ti-O thin films is reported for the first time. Although SrTiO 3 bulk is quantum paraelectric, previous reports have described that strained SrTiO 3 thin films show room-temperature ferroelectricity, especially along the in-plane direction. However, induced ferroelectricity along the out-of-plane direction has been reported in films with a limited thickness of less than 10 ml. The results show that the Sr-Ti-O thin films with spontaneously formed superlattice structures exhibit room-temperature ferroelectricity even when 300 nm thick. The induced ferroelectricity is brought about by the strain along the out-of-plane direction and is explained based on thermodynamic considerations.
We investigate the ripple pattern formation on Si surfaces at room temperature during normal incidence ion beam erosion under simultaneous deposition of different metallic co-deposited surfactant atoms. The co-deposition of small amounts of metallic atoms, in particular Fe and Mo, is known to have a tremendous impact on the evolution of nanoscale surface patterns on Si. In previous work on ion erosion of Si during co-deposition of Fe atoms, we proposed that chemical interactions between Fe and Si atoms of the steady-state mixed Fe x Si surface layer formed during ion beam erosion is a dominant driving force for self-organized pattern formation. In particular, we provided experimental evidence for the formation of amorphous iron disilicide. To confirm and generalize such chemical effects on the pattern formation, in particular the tendency for phase separation, we have now irradiated Si surfaces with normal incidence 5 keV Xe ions under simultaneous gracing incidence co-deposition of Fe, Ni, Cu, Mo, W, Pt, and Au surfactant atoms. The selected metals in the two groups (Fe, Ni, Cu) and (W, Pt, Au) are very similar regarding their collision cascade behavior, but strongly differ regarding their tendency to silicide formation. We find pronounced ripple pattern formation only for those co deposited metals (Fe, Mo, Ni, W, and Pt), which are prone to the formation of mono and disilicides. In contrast, for Cu and Au co-deposition the surface remains very flat, even after irradiation at high ion fluence. Because of the very different behavior of Cu compared to Fe, Ni and Au compared to W, Pt, phase separation toward amorphous metal silicide phases is seen as the relevant pro-
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