Analysis of uniformity of as prepared and irradiated S.I. GaAs radiation detectors
- Univ. di Modena (Italy)
- Univ. di Torino (Italy). Dipt. di Fisica Sperimentale
SI (semi-insulating) LEC (Liquid Encapsulated Czochralsky) GaAs (gallium arsenide) Schottky barrier detectors have been irradiated with high energy protons (24 GeV/c, fluence up to 16.45 {times} 10{sup 13} p/cm{sup 2}). The detectors have been characterized in terms of I/V curves, charge collection efficiency (cce) for incident 5.48 MeV {alpha}-, 2 MeV proton and minimum ionizing {beta}-particles and of cce maps by microprobe technique IBIC (Ion Beam Induced Charge). At the highest fluence a significant degradation of the electron and hole collection efficiencies and a remarkable improvement of the Full Width Half Maximum (FWHM) energy resolution have been measured with {alpha}- and proton particles. Furthermore, the reduction in the cce is greater than the one measured with {beta}-particles and the energy resolution worsens with increasing the applied bias, V{sub a}, above the voltage V{sub d} necessary to extend the electric field al the way to the ohmic contact. On the contrary, in the unirradiated detectors the charge collection efficiencies with {alpha}-, {beta}- and proton particles are quite similar and the energy resolution improves with increasing V{sub a} > V{sub d}. IBIC spectra and IBIC space maps obtained by scanning a focused (8 {micro}m{sup 2}) 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 them explain the effect of the electric field strength and the plasma on the collection of the charge carriers and the FWHM energy resolution.
- OSTI ID:
- 624192
- Report Number(s):
- CONF-971147-; ISSN 0018-9499; TRN: 98:006445
- Journal Information:
- IEEE Transactions on Nuclear Science, Vol. 45, Issue 3Pt1; Conference: Institute of Electrical and Electronic Engineers (IEEE) nuclear science symposium and medical imaging conference, Albuquerque, NM (United States), 11-13 Nov 1997; Other Information: PBD: Jun 1998
- Country of Publication:
- United States
- Language:
- English
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