Behaviour of Litihium Atoms InIII in Doped Znse
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Date
1994-02
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Addis Ababa University
Abstract
This thesis work focuses at investigating the behaviour of diffused
Lithium atoms into the II-VI semiconductor ZnSe doped with the
radioact ive dopant 111 In using the PAC (perturbed <r<r angular
correlation) technique.
The atomistic information about defects surrounding the probe atom can
be obtained using this technique.
Inorder to investigate the p-doping problems in ZnSe, PAC experiments
were conducted on ZnSe after diffusion with the potential p-type
dopant Li thium using the PAC spectroscopy. Obviously, it was found
much more difficult to prepare a p-type sample by doping ZnSe with
Lithium atoms. The failure of p-doping after doping with Lithium may
be associated with the diffusion mechanism which prevents the Lithium
atoms from occupying lattice sites in the metal sublattice, a
necessary condition for Lithium to act as an acceptor.
However, Lithium induced effects were properly investigated through
special experimental treatments and the various dependence of the
diffusion of Lithium on the matrix temperature and the vapour pressure
of Li thium were noted.
From the PAC experiments, it was observed that Li thium diffusion
introduces vacancies in the metal sublattice which are observed by
their pairing with the In probe atom. The generation of In Zn- VZn
pairs is known to occur if both the sample and the Lithium source are
held at temperatures exceeding a characteristic value.
A better understanding of the mechanism of vacancy creation during LI
incorporation might also shed new light on the problem of the missing
p-type conductivity after LI-diffusion
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Keywords
Atoms in 111in Doped Znse