engleski

Antimony-vacancy complexes in irradiated and annealed Ge crystals

Defects induced in antimony-doped germanium crystals by irradiation with either 4 MeV electrons or 1 MeV neutrons and subsequent isochronal annealing have been studied by means of deep level transient spectroscopy (DLTS) and high resolution Laplace DLTS. Samples were prepared from oxygen-lean Ge crystals with different Sb concentration in the range from 1E14 cm-3 to 2E16 cm-3.In order to obtain information on charge states of the defects direct capture cross section measurements were carried out. Information about symmetry of deep level defects was derived from LDLTS measurements under uniaxial stress. A dominant electron trap with the activation energy for carrier emission En = 0.37 eV and a dominant hole trap with Ep = 0.30 eV were assigned to the second and first acceptor levels of antimony-vacancy (Sb-V) complex, respectively. It was found that annealing rates of some radiation-induced defects depend significantly on the concentration of antimony in Ge. Particularly the annealing rate of the Sb-V complex increased with the increase in Sb content in the crystals. Possible defects reactions, which could occur upon heat-treatments in the electron-irradiated Sb-doped Ge crystals are discussed. It is argued that the main mechanism of the disappearance of the Sb-V centre is its interaction with another Sb atom that result in the formation of the Sb(2)-V complex. A hole trap with the Ep = 0.28 eV has been tentatively assigned to an acceptor level of the Sb(2)-V defect.

defects ; germanium ; neutron irradiation ; dlts

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