Method using the primary knock-on atom spectrum to characterize electrical degradation of monocrystalline silicon solar cells by space protons

Abstract

In this work, a method to calculate the equivalent dose for orbits in which the main part of the damage is due to protons, is presented. The method compares the primary knock-on atom distribution and the depth dependence of damage for the cases of space-proton irradiation and laboratory irradiation of silicon solar cells, as obtained from simulations using the transport of ions in matter code. It is shown that, in order to simulate the right depth damage distribution in space for a solar cell covered by glass, it is convenient to irradiate the cell from the backside with a proton energy dependent of the glass thickness. The method is applied to predict the electrical degradation of a silicon solar cell at the end of its life in a low altitude orbit and to estimate the damage produced as consequence of the October 19, 1989 solar proton event. The results obtained are compared with predictions of the U.S. Jet Propulsion Laboratory method.