Growth modes and epitaxy of FeAl thin films on a-cut sapphire prepared by pulsed laser and ion beam assisted deposition

Abstract

FeAl films around equiatomic composition are grown on a-cut (112¯0) sapphire substrates by ion beam assisted deposition (IBAD) and pulsed laser deposition (PLD) at ambient temperature. Subsequent successive annealing is used to establish chemical order and crystallographic orientation of the films with respect to the substrate. We find a strongly [110]-textured growth for both deposition techniques. Pole figures prove the successful preparation of high quality epitaxial films by PLD with a single in-plane orientation. IBAD-grown films, however, exhibit three in-plane orientations, all of them with broad angular distributions. The difference of the two growth modes is attributed to the existence of a metastable intermediate crystalline orientation as concluded from nonassisted sputter depositions at different substrate temperatures. The formation of the chemically ordered crystalline B2 phase is accompanied by the expected transition from ferromagnetic to paramagnetic behavior of the films. In accordance with the different thermally induced structural recovery, we find a step-like magnetic transition to paramagnetic behavior after annealing for 1 h at TA = 300 °C for IBAD deposition, while PLD-grown films show a gradual decrease of ferromagnetic signals with rising annealing temperatures.

Microstructure, magnetic properties and the giant magnetoimpedance effect of amorphous CoSiB thin films deposited by different preparation methods

“…As we know, the effect of ion bombardment during the film growth by IBAD can be described as 'local annealing' effect in the topmost few nm of the film [20]. The ions collide with atoms and surface-near atoms increasing their mobility during deposition.…”

High magnetic, transport, and optical uniaxial anisotropies generated by controlled directionally grown nano-sheets in Fe thin films

“…[30][31][32] In particular, the PLD technique enables the fabrication of amorphous ferromagnetic materials, nanostructured magnetic films, and a wide range of thin films and multilayered structures. 5,[33][34][35][36][37][38][39][40][41] In previous studies, we demonstrated that oblique PLD (oblique-angle incidence of the plasma during deposition and special geometry) of Co and Co-rich films allowed the generation of a special nano-morphology: we discovered that Cylindrical Symmetry Oblique Growth (CSOG) films were grown, composed of nano-sheets tilted ≈ 60° with respect to the substrate plane, with dimensions of ≈ 3.0-4.0 nm thickness, ≈ 30-100 nm width, and ≈ 200-300 nm length, with an inter-sheet distance of ≈ 0.9-1.5 nm, depending on the element accompanying Co, such as a transition metal V, Zn, and Cu. These nanosheets were oriented perpendicularly to the incidence plane of the plasma during deposition.…”

Manipulation of ion energies in pulsed laser deposition to improve film growth

“…This distinguishes PLD from conventional thermal evaporation like molecular beam epitaxy (MBE) where the kinetic energy of species is typically between 0.1 and 0.3 eV, and evaporation rates are rather small [3,13]. Even though it has been reported that the energetic species in the plume may induce defect formation, ion implantation, and self-sputtering in particular if the laser fluence is too high [7,[14][15][16], a certain amount of energetic species in the plume are found to be beneficial. Energetic species can promote the adatom mobility on the growing film and, thus, improve the film quality.…”