Thermodynamic and kinetic studies of pulsed laser annealing from transient conductivity measurements

Conference · Sun Jan 01 04:00:00 EST 1984

OSTI ID:6189932

Peercy, P S; Thompson, M O

Simultaneous measurements of the transient conductance and time-dependent surface reflectance of the melt and solidification dynamics produced by pulsed laser irradiation of Si are reviewed. These measurements demonstrate that the melting temperature of amorphous Si is reduced 200 +- 50/sup 0/K from that of crystalline Si and that explosive crystallization in amorphous Si is mediated by a thin (less than or equal to 20 nm) molten layer that propagates at approx. 15 m/sec. Studies with 3.5 nsec pulses permit an estimate of the dependence of the solidification velocity on undercooling. Measurements of the effect of As impurities on the solidification velocity demonstrate that high As concentrations decrease the melting temperature of Si (approx. 150/sup 0/K for 7 at. %), which can result in surface nucleation to produce buried melts. Finally, the silicon-germanium alloy system is shown to be an ideal model system for the study of superheating and undercooling. The Si/sub 50/Ge/sub 50/ alloy closely models amorphous Si, and measurements of layered Si-Ge alloy structures indicate superheating up to 120/sup 0/K without nucleation of internal melts. The change in melt velocity with superheating yields a velocity versus superheating of 17 +- 3 k/m/sec. 35 references.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6189932
• Report Number(s): SAND-84-1230C; CONF-841157-23; ON: DE85003677
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
ALLOYS
ANNEALING
ARSENIC
CRYSTALLIZATION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
GERMANIUM ALLOYS
HEAT TREATMENTS
HEATING
IMPURITIES
ION IMPLANTATION
KINETICS
LASER-RADIATION HEATING
MELTING
MELTING POINTS
OPTICAL PROPERTIES
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PLASMA HEATING
PULSE TECHNIQUES
REFLECTIVITY
SEMIMETALS
SILICON
SILICON ALLOYS
SOLIDIFICATION
SUPERHEATING
SURFACE PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE