Electron paramagnetic resonance monitoring of recovery of fast neutron irradiated GaAs

Abstract

Electron paramagnetic resonance spectra of fast neutron irradiated semi-insulating GaAs, recorded at 9 GHz and 4.2 K, have been studied as a function of isochronal thermal anneals. Their decomposition into quadruplet and singlet allows one to determine the main annealing temperatures of the corresponding defects, previously identified as As4+Ga and V2−Ga, which occur respectively at 400 and 600 °C. Comparison with the behavior of implantation damage shows that electrical activation of Be+ implants is correlated with the annealing of the main defects on the cation sublattice. Finally, the linewidth variation of the quadruplet during its decay indicates a concomitant change of the local environment of the As4+Ga center.

EL2-related studies in irradiated and implanted GaAs

“…Their results are in rather good agreement with those of Goltzene et al [38,45] presented just above. However, the dose dependance they found for the Q and S spectra imply that the S defects are located in the core region of disordered material whereas the Q centres must be located both in the cores and the surroundings shells of less-heavily damaged material [50].…”

“…Figure 6 shows the intensity variation of the two irradiation induced EPR signals, the quadruplet and singlet lines as function of isochronal annealing steps. The S line disappears completely at 450 °C while only some 90 % of the initial intensity of the quadruplet has decayed at 600 °C, the remaining signal being observable until 850 °C [45]. The thermal behaviour of the S and Q lines are very similar to that of the EL6 and U DLTS peak respectively [16] (Fig.…”

“…3). Its DLTS peak removal is well correlated with the disparition of the singlet line S in the EPR spectra [45]. Furthermore, Wosinki et al [89] observed very recently that plastic deformation of GaAs increased the concentration of EL6 traps while EL2 concentration is unchanged.…”

“…[43]. Evidence that the two defects are interacting is also given by the thermal variation of the hyperfine constant with increasing temperature [45]. These results were taken as evidence that these two defects are associated and that both the S and Q lines are generated within the same complex of intrinsic nature.…”

Positron lifetime measurements on neutron-irradiated InP crystals

“…12 However, as the rapid neutron rate and the capture crosssection at this energies are low ͑ϳb͒, one finds that the number of defects due to the ␤ recoil is very large compared with those created by the fast neutrons.…”