Current response stability of a commercial PIN photodiode for low dose radiation processing applications
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2018
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INTERNATIONAL SYMPOSIUM ON RADIATION PHYSICS, 14th
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The increasing interest in low-dose (<100 Gy) radiation processing applications, as irradiation
of blood for transplants and substerelization of insects, has demanded efforts to develop
reliable dosimetry systems with high sensitivity, good spatial resolution and stable response
over the range of 5-100 Gy. Silicon diodes fulfil these requirements and their uses in diodebased
dosimeters are deemed appropriate with the advantage of providing prompt dose-rate
and dose results. However, due to the low radiation tolerance of such dosimeters, they are
rarely employed in radiation processing, where absorbed doses of tens of kGy can be easily
achieved in regular applications.
Experimentally, the low radiation hardness of ordinary silicon diodes operating in current
mode manifests itself in a rapid drop of their current sensitivities with increasing accumulated
doses. This effect is physically attributed to the decrease of the diffusion length of minority
charge carriers, due to traps and defects induced by radiation in the silicon bulk, leading to the
decrease of sensitive volume of the diode. Consequently, it is expected that thin diodes (with
negligible thickness compared with the minority carrier diffusion lengths) are almost
insensitive to variations of diffusion lengths and hence more resistant to radiation damage
effects. From this assumption, a semiconductor dosimeter system was developed based on a
commercial thin photodiode (type SFH206K) in a p-layer/intrinsic/n-layer (PIN) structure
operating in short-circuit current mode.
In this work, the response of this diode as a dose-rate meter has been investigated with respect
the linearity between dose-rate and current, particularly addressing the stability of the current
sensitivity with the absorbed dose. The dose was gathered off-line by the integration of the
current signal during the exposure time. Irradiations were performed in both 60Co facilities of
Panoramic and Gamma Cell types, covering the dose-rate range 8-660 Gy/h.
The current-response of the diode proved to be linearly dependent on the dose-rate
characterized by a current sensitivity of 0.2 nA.h/Gy. The stability of the current delivered by
the diode for each dose-rate was evaluated as a function of the absorbed dose in several steps
from 100 Gy to 15 kGy. In all measurements, current intensities were stable during the
exposure time and proportional to the dose-rates with sensitivities variation less than 5%
(k=2).
In an attempt to lend further theoretical support to these results, calculations of the current
generated in the sensitive volume of the diode were performed taking into account its
dimensions, dose-rates and the values of diffusion lengths available in the literature. Good
agreement between theoretical and experimental results was achieved.
Como referenciar
GONÇALVES, JOSEMARY A.C.; MANGIAROTTI, ALESSIO; BUENO, CARMEN C. Current response stability of a commercial PIN photodiode for low dose radiation processing applications. In: RUBIO, MARCELO (ed.); TIRAO, GERMAN (ed.). In: INTERNATIONAL SYMPOSIUM ON RADIATION PHYSICS, 14th, October 7-11, 2018, Córdoba, Argentina. Abstract... Córdoba: Centro de Excelencia en Productos y Procesos, 2018. p. 308-308. Disponível em: http://repositorio.ipen.br/handle/123456789/29750. Acesso em: 30 Dec 2025.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.