Papers by Author: Noriaki Ikenaga

Abstract: We have found that deposited film can be crystallized without the post-annealing treatment but with the simultaneous ion-irradiation during sputter-deposition at very low substrate temperature. The present paper reviews the low temperature crystallized TiNi films deposited by the above technique. An RF magnetron sputtering apparatus equipped with separate confocal sources as well as with a heating and ion-irradiating system for substrates was used to make the films crystalline. Without using the ion-irradiating system, the films deposited on ambient-temperature substrate have been amorphous. However, crystallized film is deposited even at 353 K of substrate temperature with using the system. Appropriate ion-irradiation is considered to be help to crystallize the film at low substrate temperature. Broad and doublet X-ray diffraction profile of the film, which was diffracted from B19’ and/or R phase, was recorded between 42 degree to 45 degree in 2 theta. The crystallized film deposited on a polyimide sheet was cut into the shape of a double-beam cantilever and the ends of the two beams were connected to an electrical power supply. The cantilever shows a repeatable two-way motion by electrical cycle of 0.1 Hz at room temperature.

Abstract: In the last years oxide materials for electronics show significant progress. However, many details regarding technology control of the properties have to be solved. For electronics, thin films and heterestructures are important taking advantage of integration and synergetic concepts leading to new types of devices and functionalities. It is notable that, while fabrication of new devices and materials showing new phenomena are booming, the growth principles and concepts are somehow developing slowly within this general trend. This is because in many cases, growth of materials is very personalized. Understanding of the bi-directional relationship between the general and particular principles deserves attention. The immediate benefit is that knowledge on growth for one material can be transferred to another one. In our work we have analyzed such relationships for some oxide multicomponent perovskites. Materials used in our examples are Bi-Sr-Ca-Cu-O and YBa₂Cu₃O₇, (Ca, Sr)CuO₂, (Ca, Ba)CuO₂ and Bi₄Ti₃O₁₂. Presented thin films or heterostructures are with c-axis and non-c-axis orientations and based on these examples we discuss some of the growth principles.

Abstract: In order to fabricate two-dimensional micro actuators with shape memory alloy films, it is especially important to evaluate the anisotropy of transformation strain that is caused by texture. In this paper, microstructures of sputter-deposited TiNi films are examined. The films of 1 μm in thickness are sputter-deposited on Si(001) substrates by RF magnetron multi-sputtering system equipped with four separate confocal sources as well as with substrate heating. Pure Ti and Ni targets of 50 mm in diameter are used for the sources. The films deposited at ambient temperature have been generally amorphous. However, we find that some films which are deposited at 773K of substrate temperature are crystalline, when we appropriately choose sputtering parameters such as source voltage and the distance between a target and the substrate. X-ray powder diffraction and pole figure measurements reveal that these films are oriented with {110}B2 parallel or inclined at 45 degree to the substrate. Furthermore, we also find that crystallized film is deposited even at 673K of substrate temperature by applying pulse bias voltage to the substrate.