P. Dahan et V. Fleurov, POSSIBILITY OF A METASTABLE STATE FOR A TRANSITION-METAL IMPURITY IN SEMICONDUCTOR, Physical review. B, Condensed matter, 53(19), 1996, pp. 12845-12854
A transition-metal impurity in a semiconductor can be shifted from its
high symmetry substitutional position due to the Jahn-Teller interact
ion. An interplay of the spin-orbit and Jahn-Teller interactions may l
ead to a double-well potential for such an impurity in the configurati
on coordinates. One of these new states can be metastable and characte
rized by extremely long relaxation time especially at low temperatures
. This allows us to explain the observation of the line complementing
the intracenter transition line to the forbidden energy gap both in th
e luminescence and in the photoluminescence excitaton spectra. Various
other puzzling experimental observations are discussed and explained
on the basis of this mechanism.