Modeling of undercooling, nucleation, and multiple phase front formation in pulsed laser melted amorphous silicon

Conference · Sat Dec 01 04:00:00 EST 1984

OSTI ID:6466621

Wood, R F; Geist, G A; Solomon, A D; Lowndes, D H; Jellison, Jr, G E

Recently available experimental data indicate that the solidification of undercooled molten silicon prepared by pulsed laser melting of amorphous silicon is a complex process. Time-resolved reflectivity and electrical conductivity measurements provide information about near-surface melting and suggest the presence of buried molten layers. Transmission electron micrographs show the formation of both fine and large-grained polycrystalline regions if the melt front does not penetrate through the amorphous layer. We have carried out extensive calculations using a newly developed computer program based on an enthalpy formulation of the heat conduction problem. The program provides the framework for a consistent treatment of the simultaneous formation of multiple states and phase-front propagation by allowing material in each finite-difference cell to melt, undercool, nucleate, and solidify under prescribed conditions. Calculations indicate possibilities for a wide variety of solidification behavior. The new model and selected results of calculations are discussed here and comparisons with recent experimental data are made.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6466621
• Report Number(s): CONF-841157-100; ON: DE86002192
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
AMORPHOUS STATE
ELEMENTS
HEATING
LASER-RADIATION HEATING
MELTING
NUCLEATION
OPTICAL PROPERTIES
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PLASMA HEATING
REFLECTIVITY
SEMIMETALS
SILICON
SOLIDIFICATION
SURFACE PROPERTIES