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Analysis of Uniformity of as Prepared and Irradiated S.I. GaAs Radiation Detectors.

Presented at IEEE - Nuclear Science Symposium 1997 - Albuquerque (USA), 9-15 November 1997, to be published on IEEE - NSS97 Conference Records

F. Nava1, P. Vanni1, C. Canali2, C. Manfredotti3, P. Polesello3, E. Vittone3, G. Egeni4, V. Rudello4

1 Dipartimento di Fisica, Universitá di Modena, Via Campi 213/A, 41100 Modena, Italy.

2 Dipartimento di Scienze dell’Ingegneria, Universitá di Modena, Via Campi 213/A, 41100 Modena, Italy.

3 Dipartimento di Fisica Sperimentale, Universitá di Torino, Via Giuria 1, 10125 Torino, Italy.

4 INFN, Laboratori Nazionali di Legnaro, Via Romea 4, Legnaro (PD), Italy

Key Words: GaAs nuclear detector, IBIC



The performance of GaAs unirradiated and proton irradiated detectors as a spectrometry devices has been tested by measuring the energy resolution for incident 2 MeV proton particles and the charge collection efficiency by microprobe technique IBIC (Ion Beam Induced Charge).

The energy resolution improves with increasing the proton fluence at a given applied voltage, Va, above the voltage Vd necessary to extend the electric field all the way to the ohmic contact and worsens with increasing Va>Vd. On the contrary, in the unirradiated detectors the energy resolution improves with increasing Va > Vd.

IBIC spectra and IBIC space maps obtained by scanning a focused (8 m2) 2 MeV proton microbeam on front (Schottky) and back (ohmic) contacts, support the observed electric field dependence of the energy resolution both in unirradiated and most irradiated detectors.

The results obtained let us explain the effect of the electric field strength and the plasma on the energy resolution.