Comparison of crystallization kinetics in a-Si∕Cu and a-Si∕Al bilayer recording films under thermal annealing and pulsed laser irradiation

Abstract

Under thermal annealing, the crystallization temperatures of a-Si in a-Si/ Cu and a-Si/ Al bilayer recording films were significantly reduced to around 485 and 357°C, respectively, and the activation energies for crystallization were reduced to about 3.3 eV. The formation of Cu 3 Si phase prior to crystallization of a-Si was found to occur at around 175°C in a-Si/ Cu, while no Al silicide was observed in a-Si/ Al before crystallization of a-Si. The reaction exponents for a-Si/ Cu and a-Si/ Al were determined to be around 1.8 and 1.6, respectively, corresponding to a crystallization process in which grain growth occurs with nucleation, and the nucleation rate decreases with the progress of grain growth. Under pulsed laser irradiation, the precipitation of Cu 3 Si phases and crystallization of a-Si were observed in a-Si/ Cu, while the crystallization and reamorphization of a-Si took place sequentially in a-Si/ Al. The reaction exponents for a-Si/ Cu and a-Si/ Al, determined to be about 2.0 and 2.2, respectively, are slightly higher than those under thermal annealing, indicating that the crystallization processes of a-Si/ Cu and a-Si/ Al under pulsed laser irradiation are similar to those under thermal annealing. However, the decrease of nucleation rate with the progress of grain growth is slower. At the same time, the activation energies for crystallization of a-Si/ Cu and a-Si/ Al, estimated to be about 0.18 and 0.22 eV, respectively, are nearly an order of magnitude lower than those under thermal annealing. This may be explained by the explosive crystallization of a-Si by mechanical impact, with a high power pulsed laser.

Ge/Al bilayer thin film for optical write-once media

“…The increase of resistance is owing to the thickness decrease of Al layer. On the other hand, the increase and decrease of resistance from 275 °C to 380 °C is owing to the reamorphization and p.r ann Atomic Percent Gernioniule Ge segregation of Ge and Al grain, this result is the same as a-Si/Al bilayers [8]. The GeAl has a simple eutectic curve and an eutectic line at 420 °C, as shown in the GeAl phase diagram of figure 5 [11].…”

“…It can be seen that the crystallization temperature of Ge is reduced from 473 °C to 275 °C in the Ge/Al bilayer structure due to the metal induced crystallization (MIC) mechanism. [4,8,10,12] 0 100 200 300 400 500…”

“…The crystallization temperature of sandwiched structure a-Si:H/Ag/a-Si:H [4] was found lower than that of a-Si/Ag/a-Si. The bilayer structure, such as a-Si/Ni [5], Si/Cu [6], Sb/Se [7] and a-Si/(Cu, Al) [8] were also been studied for the inorganic recording media recently.…”

Characterization of write-once blu-ray disk containing Cu–Al/Si recording layer using transmission electron microscopy

“…As a popular high-speed recording medium for writeonce blu-ray disk ͑BD-R͒, the Cu/Si bilayer has been widely studied for its microstructure and correlation to signal properties. 1-9 Various tools, namely, Auger electron spectroscopy ͑AES͒, 3,4 transmission electron microscopy ͑TEM͒, 6 phase-change kinetics of thin films, 7,8 and conductive atomic force microscopy ͑C-AFM͒, 9 have been employed to analyze the operative mechanism of Cu/Si-based BD-R disk samples. AES revealed a diffusion of Si into Cu and a formation of CuSi alloy containing 25-30 at.…”

The transition from linear to-parabolic growth of Cu3Si phase in Cu/a-Si system

“…From a fundamental point of view, the case where the bond weakening of the a-Si is achieved by a solid state reaction is especially interesting (e.g. Ni in Ref [9] or Cu in Ref [10]).…”