Nk. Huang et al., THE BEHAVIOR OF RADIATION-DAMAGE OF NB-IMPLANTED SAPPHIRE AFTER ANNEALING AT REDUCING ATMOSPHERE( ION), Physica status solidi. a, Applied research, 165(2), 1998, pp. 367-376
Sapphire crystals with (0001) and (01 (1) over bar 2) orientations wer
e implanted with 380 keV Nb+ ions to a dose of 5 x 10(16) ions/cm(2) a
t room temperature and 100 K. The behavior of the radiation damage pro
duced by ion implantation followed by annealing with a series of steps
from 500 to 1100 degrees C at reducing atmosphere is investigated usi
ng optical absorption technique. The absorption curves were evaluated
by Gaussian fitting based on the well known F-type centers, which were
confirmed by luminescence measurements. The results of optical densit
y (OD) from the bands with annealing: temperature and time show that t
he annealing behavior of the radiation damage produced by Nb+ ion impl
antation call be divided into three stages. The First stage is in tile
range of annealing from 500 to 800 to 900 degrees C; the second is fr
om 900 to 1000 degrees C: the third is one above 1000 degrees C. Defec
ts mere annealed within these stages due to different mechanisms which
are proposed on the basis of the optical absorption measurements comb
ined with the observation of SEM micrographs and colour variation of t
he sample after annealing steps with temperature.