Direct Measurement of Cw Laser-Induced Crystal Growth Dynamics by Time-Resolved Optical Reflectivity
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Hess,
and Sigmon,
eds.
Laser andElectron-Bean, Solid Interactions and materials Processing
125
DIRECT MEASURE4ENT OF CW LASER-INDUCED CRYSTAL GROWTH DYNAMICS BY TIME-RESOLVED OPTICAL REFLECTIVITY
G.L. OLSON, S.A. KOKOROWSKI, J.A. ROTH AND L.D. HESS Hughes Research Laboratories, Malibu, California 90265
ABSTRACT We report the use of time-resolved optical reflectivity to directly monitor the dynamics of cw laser-induced solid phase This in situ measurement techepitaxy (SPE) of thin films. nique utilizes optical interference effects between light reflected from the surface of a sample and from an advancing interface to provide continuous temporal and spatial resoluSPE growth rates of iontion of crystal growth processes. implanted films which are five orders of magnitude faster than previously observed can be induced and accurately meaArsenic enhances the SPE rate, sured with the laser method. and spatially resolved measurements show that the growth rate for arsenic implanted films varies in accordance with the ion implantation profile. Results are reported for silicon selfimplanted samples with and without subsequent arsenic ion implantation, and for silicon samples directly implanted with arsenic.
INTRODUCTION Solid phase epitaxial crystallization of ion-implanted and deposited amorphous films is a process of significant technological importance and is a subject of continuing scientific research [i]. Current research activities in this field include the determination of the kinetics and mechanisms of the crystal reconstruction process at the crystalline/subcrystalline interface present in ion-implanted films, study of impurity effects, development of a quantitative description of the kinetically competitive processes of epitaxial crystallization and polycrystallite formation, and the investigation of rapid solid phase crystal growth kinetics and defect propagation at the elevated temperatures encountered during cw laser annealing of ion-implanted and/or deposited films on crystalline substrates. In this paper we report results of studies conducted with the use of a recently developed optical reflectivity method [2] for directly monitoring the real-time behavior of laser-induced solid phase epitaxy (SPE) in regimes of time, temperature and spatial resolution that were previously inaccessible. This in situ measurement technique relies on optical interference effects between light reflected from the surface of a sample and from an advancing interface to provide continuous temporal and spatial resolution of crystal (1) monitor the formation and growth processes. We have used this method to: propagation of a laser-induced epitaxial growth interface in ion-implanted and UHV deposited films on various substrates, (2) examine the effects of single and multiple implanted impurities as well as sputter processes on epitaxial growth rates, (3) investigate the competition between SPE and polycrystallite formation in air and in UHV environments, and (4) extend previous SPE rate measurements Specific by more than five order
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