Can the crystallization rate be independent from the crystallization enthalpy? The case of amorphous silicon.
The crystallization enthalpy measured in a large series of amorphous silicon (a-Si) materials varies within a factor of 2 from sample to sample (Kail et al 2011 Phys. Status Solidi RRL 5 361). According to the classical theory of nucleation, this variation should produce large differences in the crystallization kinetics leading to crystallization temperatures and activation energies exceeding 550 °C and 1.7 eV, respectively, the 'standard' values measured for a-Si obtained by self-implantation. In contrast, the observed crystallization kinetics is very similar for all the samples studied and has no correlation with the crystallization enthalpy. This discrepancy has led us to propose that crystallization in a-Si begins in microscopic domains that are almost identical in all samples, independently of their crystallization enthalpy. Probably the existence of microscopic inhomogeneities also plays a crucial role in the crystallization kinetics of other amorphous materials and glasses.
GRMT, Department of Physics, University of Girona, Montilivi Campus, E17071-Girona, Catalonia, Spain.
F
F
Kail
J
J
Molera
J
J
Farjas
P
P
Roura
C
C
Secouard
P
P
Roca i Cabarrocas
D002152:Calorimetry, Differential Scanning; D003460:Crystallization; D007700:Kinetics; D012825:Silicon / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics
D012825:Silicon