Influence of acceptor impurities on semi-insulating GaAs particle detectors
INFM, Dipartimento di Fisica "A. Volta" dell'Università, Via Bassi 6, 27100 Pavia, Italy
2 Dipartimento di Fisica dell'Università, Via Campi 213/a, 41100 Modena, Italy and INFN- Bologna, Italy
3 ALENIA.MARCONI S.p.a., Via Tiburtina km 12.400, 00131 Roma, Italy
Published online: 15 July 2000
GaAs Schottky diodes, made on semi-insulating liquid encapsulated Czochralski grown material with concentrations of acceptor dopants Na varying from 1014 to 1017 cm-3, were investigated as alpha particle detectors. The charge collection efficiency (CCE) was found to decrease dramatically with increasing Na. Optical spectra in transmittance and reflectance were accurately measured to determine the concentrations of both neutral and ionised EL2 defects as a function of Na. The concentration of ionised EL2+ centres was shown to increase with Na, and to be quasi inversely proportional to the CCE values. This behaviour strongly supports the hypothesis that the EL2 defects play the main role in the compensation of the material and in limitation of the detection properties.
PACS: 29.40.Wk – Solid-state detectors / 78.70.-g – Interactions of particles and radiation with matter / 71.55.-i – Impurity and defect levels
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000