Epitaxial growth mechanisms and structure of CaF[sub 2]/Si(111)

Journal Article · Tue Nov 15 00:00:00 EST 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.50.14340· OSTI ID:6996356

Lucas, C A; Loretto, D; Wong, G C.L. ^[1]

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1. Materials Sciences Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (United States)

The early stages of interface formation between CaF[sub 2] and Si(111) have been studied, [ital in] [ital situ], by a combination of reflection high-energy electron diffraction, x-ray diffraction, and core-level photoemission. The results are combined with [ital ex] [ital situ] transmission-electron-microscopy measurements to show that the initial growth mode changes from Volmer-Weber to Stranski-Krastanow, depending on the substrate temperature. The crossover is correlated with a submonolayer transition from the Si(111)-(7[times]7) to a (3[times]1) reconstruction. This is accompanied by fluorine dissociation at the interface. Both initial growth modes can lead to a uniform CaF[sub 2] epilayer and subsequent growth on this surface is layer by layer. Using x-ray crystal truncation-rod analysis, we have examined the CaF[sub 2]/Si(111) surface and interface structure. For films grown at temperatures above the (7[times]7)[r arrow](3[times]1) transition, the Ca atom in the CaF layer at the interface is located in a single [ital T][sub 4] bonding site. Finally, we have observed a structural transition at the interface from the as-grown structure to a ([radical]3 [times] [radical]3 )[ital R]30[degree] reconstruction, which appears to be incommensurate. The dynamics of this transition and the possible mechanisms will be discussed.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6996356
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 50:19; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CALCIUM FLUORIDES
CHEMISORPTION
CRYSTAL-PHASE TRANSFORMATIONS
SILICON
SORPTIVE PROPERTIES
CRYSTAL GROWTH
DIFFUSION
EPITAXY
INTERFACES
KINETICS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 1000-4000 K
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CALCIUM HALIDES
CHEMICAL REACTIONS
COHERENT SCATTERING
DIFFRACTION
ELECTRON MICROSCOPY
ELEMENTS
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
MICROSCOPY
PHASE TRANSFORMATIONS
SCATTERING
SEMIMETALS
SEPARATION PROCESSES
SORPTION
SURFACE PROPERTIES
TEMPERATURE RANGE
360602* - Other Materials- Structure & Phase Studies