Deposition of Cu Films for Laser Mirror by Partially Ionized Beam Deposition
- PDF / 357,175 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 105 Downloads / 203 Views
ABSTRACT Partially ionized beam deposition of Cu thin films on glass at room temperature were carried out to fabricate Cu laser mirrors with good structural and reflectance properties. At a constant film thickness of 600 A, the grain size of as-grown Cu films increased with acceleration voltage, and there was no indication of defects such as cracks and/or large pores in the film surface as shown in scanning electron microscopy images. Root-mean-square(Rs) surface roughnesses of the films with thicknesses of 600 A were measured by atomic force microscopy. Rls surface roughness increased when acceleration voltage increased from 0 kV to 2 kV, but decreased at the acceleration voltage of 3 kV. Rms surface roughness of the film grown at 4 kV, however, increased again. At the acceleration voltage of 3 kV, reflectance of the films increased with the film thickness until 600 A and decreased at the film thickness of 800 A. The reflectance results showed that the Cu film deposited at 3 kV had higher reflectance than that of others. Our results suggest that it is possible to grow the Cu film with good structural and optical properties on glass substrate at room temperature by partially ionized beam deposition.
INTRODUCTION A laser with a sharply monochromatic beam can be used in many kinds of precise machine
tools because of its high power and its ability to focus into a microspot[l]. In order to perform effectively in machining by laser, a laser mirror is one of the important parts. Significant factors of the metal film for the laser mirror are high density, good adhesive force, sharp interface and low surface rougbness[2]. Many kind of metals, such as Aluminium (Al), Gold (Au) and Copper (Cu) are used as reflective coatings in the infrared range[3]. Al is easy to evaporate in vacuum and has good ultraviolet, visible and infrared reflectance. Al, however, easily forms an aluminium oxide which is detrimental to reflectance and has a lower intrinsic reflectance than other metals. Au is probably the best material for infrared reflecting coatings. Since the Au reflectance in the visible range decreases abruptly, it was usually used above the wavelength of 700 um. Au film on glass tends to be rather soft and damages easily. Moreover the biggest disadvantage is its high expense to fabricate. Cu has a reflectancesimilar to Au. Another advantage is that it is haerder to oxidize than Al and cheaper than other metals[4]. Partially ionized beam deposition (PIBD) is one of the ion-assisted film deposition techniques, which was reported by many researchers[5-6]. The PLBD has been paid great attention in many areas of thin film preparation, because high quality metal films can be fabricated[7]. In order to fabricate a laser mirror with good reflectance property, we attempted to grow Cu films on glass by PIBD system at room temperature. Structural and optical properties of the Cu films deposited at various acceleration voltages (Va) are been discussed.
575 Mat. Res. Soc. Symp. Proc. Vol. 396 01996 Materials Research Society
EXPERIMENT
Data Loading...
