Influence of Substrate Temperature on Barium Ferrite Films Prepared by Laser Deposition
- PDF / 986,897 Bytes
- 6 Pages / 412.92 x 637.2 pts Page_size
- 28 Downloads / 215 Views
Inflence of Substrate Temperature on Barium Ferrite Films Prepared by Laser Deposition W.D. Song, Y.F. Lu, W.J. Wang, T.C. Chong, Laser Microprocessing Laboratory, Department of Electrical Engineering and Data Storage Institute, 10 Kent Ridge Crescent, Singapore 119260 ABSTRACT Influence of substrate temperature on properties of barium ferrite films prepared by laser deposition is studied in this paper. The magnetic properties, grain shape and crystalline orientation of the films are discussed for the films prepared by laser deposition with in-situ heating, post annealing and varying substrate temperature. The results show that magnetic properties, grain shape and crystalline orientation of the film deposited with varying substrate temperature are close to the film deposited with post-annealing and different to the film deposited with in-situ heating. INTRODUCTION In the last few years, the area density of rigid disk has been increasing at an annual growth rate of 60%. If this growth rate continues, 40 Gb/in 2 drives will be on the market around year 2003 [1]. In order to realize such area density, it is necessary to develop media material with coercivity of 5 kOe and above [1]. Barium ferrite has been identified as one of the candidates for magnetic recording since it possesses both high coercivity and good mechanical and chemical stability [2,3]. Presently, barium ferrite films have been prepared by a few groups using sputtering either applying in situ substrate heating during deposition or through a post annealing process [314]. For in-situ heating, substrates are heated up to a certain temperature before deposition starting, then substrate temperature is kept constant during film growth. After that, films are cooled down to room temperature. In contrast, for post annealing, films are grown at room temperature or a low temperature. The films are then processed with a post annealing. Both methods have been widely used in sputtering and laser deposition. For these two methods, the substrate temperature is always constant during film growth. Since substrate temperature is one of the key parameters to the film quality, it is of interest to investigate the influence of varying substrate temperature on film properties. In this paper, we report laser deposition of barium ferrite films with in-situ heating, post-annealing and varying substrate temperature during film growth. EXPERIMENTAL The experimental setup of laser deposition system was discussed elsewhere [14]. A KrF excimer laser beam was focused onto a rotating target with a lens to produce a laser fluence of about 3 J/cm 2 . A barium ferrite (BaFe120 19) target was mounted at 450 with respect to the laser beam. Facing the target at a distance of 4 cm from it, (001) single-crystal A120 3 substrates were mounted on a stainless steel holder by silver paste. A background pressure of 105 Torr was achieved with a turbomolecular pump. During the deposition, about 250 mTorr pressure of flowing oxygen was maintained. The first group of films was prepared by laser depositi
Data Loading...
