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Pressure-enhanced interdiffusion in amorphous Si/Ge multilayers Steven D. Theiss,a)

Summary: Pressure-enhanced interdiffusion in amorphous Si/Ge multilayers
Steven D. Theiss,a)
Frans Spaepen, and Michael J. Azizb)
Division of Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
Received 2 November 1995; accepted for publication 28 December 1995
We have investigated the effect of hydrostatic pressure on interdiffusion in multilayers composed of
alternating layers of amorphous Si 2.7 nm and Ge 3.1 nm . Samples were annealed at 420 C at
pressures between 0 and 2.8 GPa in an externally heated diamond anvil cell. Interdiffusion was
measured by monitoring the decay with annealing time of the intensity of the first-order x-ray
reflection resulting from the effects of composition modulation. The decay curves for all pressures
could be made to coincide by scaling the annealing times. This made it possible to separate the
effects of pressure on the interdiffusivity from those of composition and structural relaxation. The
interdiffusivity increased with applied pressure, with an activation volume of 5.0 cm3
/mole, or
0.42 times the atomic volume of crystalline Si. 1996 American Institute of Physics.
S0003-6951 96 01109-9
The rates of atomic transport processes, such as diffu-
sion, decrease with increasing pressure in most materials.1
However, in some materials with an open covalent network
structure, such as GeO2 Ref. 2 and some silicate melts,3,4


Source: Aziz, Michael J.- School of Engineering and Applied Sciences, Harvard University


Collections: Physics; Materials Science