Of. Hagena et al., MAGNESIUM CLUSTER-BEAM DEPOSITION ON GLASS AND SI(111), Journal of vacuum science & technology. A. Vacuum, surfaces, and films, 12(2), 1994, pp. 282-288
Citations number
18
Categorie Soggetti
Physics, Applied","Materials Science, Coatings & Films
Magnesium cluster beams have been obtained from supersonic nozzle expa
nsions. The low boiling point of Mg (1363 K) allows conditions for clu
stering to be reached with and without argon as a carrier gas. This ar
ticle reports on cluster size and intensity as a function of expansion
conditions, and discusses the characteristics of magnesium films obta
ined by cluster-beam deposition. The source parameters were temperatur
e T0 less-than-or-equal-to 1600 K, total pressure p0 less-than-or-equa
l-to 5000 hPa, magnesium partial pressure p(Mg) less-than-or-equal-to
2600 hPa, supersonic conical nozzle: diameter d = 0.25 mm, cone angle
2alpha = 10-degrees, and cone length l = 27 mm. For the Ar/Mg mixture
the cluster-beam intensity corresponded to deposition rates of up to 8
3 nm/s at a 0.3 m distance from the nozzle. This exceeds the ''ideal''
intensity from a sonic nozzle operated with the same magnesium mass f
low by about a factor of 3.5. For the neat Mg vapor the deposition rat
es extended up to 190 nm/s, but at a higher Mg mass flow compared to t
he Ar/Mg mixture. The cluster beams were deposited on room-temperature
glass and Si(111) substrates. Films about 1000 nm thick were examined
by x-ray diffraction. Compared to films produced by atomic beam depos
ition with a typical polycrystalline structure the cluster films are d
istinguished by a preferential orientation of (002) planes parallel to
the substrate. This feature was observed for both types of cluster be
ams, with and without argon as a carrier gas, and for both glass. and
Si substrates. The highly specular film surfaces turned usually into a
golden-yellow color after, exposure to air, with the notable exceptio
n of the film formed with the highest intensity (510 nm/s). The surfac
e structure studied with an atomic force microscope showed an increase
in grain size with increasing deposition rate.