Premium
Angular dependence of dose sensitivity of surface diodes
Author(s) -
Jursinic Paul A.
Publication year - 2009
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3125644
Subject(s) - sensitivity (control systems) , diode , dosimetry , materials science , optics , medical physics , physics , nuclear medicine , optoelectronics , medicine , electronic engineering , engineering
Commercially available surface diodes are found to have as great as ±12% change in sensitivity with the angle of incidence of radiation. This work is a study of the cause of angular dependence in diode sensitivity and how it can be decreased. A number of different surface diodes were used in these measurements: A commercially available diode and four prototype diodes. A number of the diodes were constructed with the silicon chip, the die, mounted on a circuit board that had a plane of copper on its back side. These diodes had angular dependence of sensitivity as great as ±10%. It was hypothesized that the copper plane on the circuit board was the cause of the anisotropy in sensitivity of the diodes. To test this hypothesis, diodes with a new design [Patent No. 61/035,257 (pending)], without a copper back plane, were fabricated and characterized in this work. These diodes were found to have the following characteristics: A dependence on incident angle of radiation of ±3.6%; after 10 kGy of pre‐irradiation, a 1.6% change in sensitivity for a 260‐fold change in dose per pulse; an areal density of 0.08 g / cm 2 .