Dead layer on silicon p-i-n diode charged-particle detectors

• Published in: arXiv.org 2013-10
• Main Authors: Wall, B L, Amsbaugh, J F, Beglarian, A, Bergmann, T, Bichsel, H C, Bodine, L I, Boyd, N M, Burritt, T H, Chaoui, Z, Corona, T J, Doe, P J, Enomoto, S, Harms, F, Harper, G C, Howe, M A, Martin, E L, Parno, D S, Peterson, D A, Petzold, L, Renschler, P, Robertson, R G H, Schwarz, J, Steidl, M, Van Wechel, T D, VanDevender, B A, Wüstling, S, Wierman, K J, Wilkerson, J F
• Format: Article
• Language: English
• Subjects: Charged particles; Computer simulation; Depletion; Diffusion layers; Energy measurement; Energy spectra; Ionization; Neutrinos; Radiation counters; Semiconductor charged particle detectors; Silicon
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1310.1178

Semiconductor detectors in general have a dead layer at their surfaces that is either a result of natural or induced passivation, or is formed during the process of making a contact. Charged particles passing through this region produce ionization that is incompletely collected and recorded, which leads to departures from the ideal in both energy deposition and resolution. The silicon \textit{p-i-n} diode used in the KATRIN neutrino-mass experiment has such a dead layer. We have constructed a detailed Monte Carlo model for the passage of electrons from vacuum into a silicon detector, and compared the measured energy spectra to the predicted ones for a range of energies from 12 to 20 keV. The comparison provides experimental evidence that a substantial fraction of the ionization produced in the "dead" layer evidently escapes by diffusion, with 46% being collected in the depletion zone and the balance being neutralized at the contact or by bulk recombination. The most elementary model of a thinner dead layer from which no charge is collected is strongly disfavored.