Abstract
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In this paper, the performance of an “edgeless”
device is evaluated for use as an angular independent detector for
dosimetric quality assurance in radiotherapy. The edgeless diodes
were tested in terms of current–voltage (IV) and capacitance–
voltage (CV) characteristics, charge collection efficiency and
radiation hardness. A model of the edgeless device was developed
to simulate the distribution of the electric field for different
geometries using technology computer aided design (TCAD). IV
and CV characteristics of the diodes indicate the appropriate
operational conditions and provide a means to assess the consistency/
quality of the edgeless diode technology. TCAD model
shows good agreement with experimental results demonstrating
the accuracy of the model in simulating the behavior of the edgeless
diodes. The charge collection efficiency is evaluated for two of
the edgeless configurations PP and NP. The angular dependence
measurements of edgeless devices before and after 2 Mrad irradiation
shows negligible effect of radiation damage on response as
a function of the angle. The experimental data are supported by
the results of the TCAD simulation study, which indicates negligible
impact of radiation damage from a clinical use perspective.
Both the experimental and simulated results derived from the
radiation damage study show minimal degradation (within 4%)
of the diodes sensitivity.