Self-diffusion in intrinsic germanium single
crystals has been investigated over the temperature range 822-1163K using 71Ge
as radioisotope and a sputtering technique for serial sectioning. The data can
be described by a preexponential factor of (2.48+or-0.6)*10-3 m2 s-1 and an
activation enthalpy of (3.14+or-0.92) eV. The present data are discussed
together with literature data obtained with conventional sectioning techniques
at higher temperatures. The self-diffusion coefficients at 870 and 894K were also
measured for Ga-doped (1.7*1018 atoms cm-3) and Sb-doped (1.8*1018 atoms cm-3)
samples. The diffusivity is higher in n-type and lower in p-type germanium than
in intrinsic material. Since it is known that a vacancy in germanium acts as an
acceptor the observed direction and order of magnitude of the doping dependence
can be understood in terms of the shift of the Fermi level in doped crystals.
This supports the view that self-diffusion in germanium proceeds by a vacancy
mechanism.
Source:IOPscience
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