Abstract
This study focused on preparation of the ternary and quaternary alloys by doping Ag as well as co-doped with Ag and Cr or Ag and V to the binary alloy GeSb9. By the measured results of film concentration, grain sizes, microstructures, thermal, optical and erasing characteristics, we estimate the feasibility of GeSb9 based alloys as high density phase change optical disk recording materials. The high-resolution transmission electron microscopy (HRTEM) observations revealed that the grain sizes reduced with increasing doping concentrations. As the Ag, Ag+Cr and Ag+V concentration reached 3.9 at.%, 5 at.% and 2.8 at.%, the grain sizes reduced from the original GeSb9 grain size (120~300nm) to 10~30nm, 10~30nm and 10~40nm, respectively. X-ray diffraction was applied to identify phases of the films, and only Sb diffraction peaks were observed in each alloy film. The results of differential scanning calorimeter (DSC) showed that GeSb9 doped with Ag, Ag+Cr or Ag+V will have lower crystallization temperatures, i.e. between 172℃ and 158℃, than that of undoped GeSb9 (187℃). After doping Ag or co-doped with Ag and Cr (Ag: 3.5 at.%, Cr: 1.5 at.%), the crystallization activation energies of the ternary and quaternary alloys are between 2.8eV~1.79eV. However, when co-doped with Ag and V (Ag: 1.2 at.%, V: 0.4 at.% and Ag: 2.3 at.%, V: 0.5 at.%), the crystallization activation energy (3.9 and 2.9eV, respectively) will be higher than that of GeSb9. For all the ternary and quaternary alloys under study, the optical reflection contrasts were lower than those of GeSb9 binary alloy (about 22%) at short wavelengths (460nm and 405nm). From static testing results, it can be found that the crystallization rate of GeSb9+Cr*1 ternary alloy and GeSb9+Ag*1+Cr*1 quaternary alloy were higher than that of GeSb9 binary alloy.