HALL-EFFECT MEASUREMENTS ON PROTON-IRRADIATED ROSE SAMPLES

Bulk samples obtained from two wafers of a silicon monocrystal materia l produced by float-zone refinement have been analysed using the four- point probe method. One of the two wafers comes from an oxygenated ing ot; two sets of pure and oxygenated samples have been irradiated with 24 GeV/c protons in the fluence range from 10(13) to 1.74 x 10(14) p/c m(2). Van der Pauw resistivity and Hall coefficient have been measured before and after irradiation as a function of the temperature. A ther mal treatment (30 min at 100 degrees C) has been performed to accelera te the reverse annealing effect in the irradiated silicon. The irradia ted samples show the same exponential dependence of the resistivity an d of the Hall coefficient on the temperature corresponding to the pres ence of radiation-induced deep energy levels around 0.6-0.7 eV in the silicon gap. The free carrier concentrations (n, p) have been evaluate d in the investigated fluence range. The inversion of the conductivity type from n to p occurred, respectively, at 7 x 10(13) and at 4 x 10( 13) p/cm(2) before and after the annealing treatment for both the two sets. Only slight differences have been detected between the pure and the oxygenated samples.