Analysis of radiation damage in silicon by thermal annealing of solar cells

Abstract

Abstract Thermal annealing of the photovoltaic parameters of silicon solar cells irradiated at room temperature by electrons (15 to 45 MeV), protons (5 MeV) and fast neutrons has been studied up to a temperature of 500 °C. The cells were prepared from single crystals grown by the Czochralski process (oxygen ∼1018/cm3) by the float-zone technique (oxygen ∼ 1016/cm3), each doped with boron or aluminum. The radiation damage was observed to anneal in two characteristic stages. The first stage occurs between 50° and 200°C and is independent of dopant type, of dopant concentration, and of the concentration of oxygen impurity. It is suggested that this stage is due to the breaking-up of clusters of recombination centers. In the second stage, observed between 275° and 450°C. the remaining damage produced by bombardment is removed. Unlike the low temperature stage, it is strongly dependent on the nature of the dopant and oxygen impurity concentration and bears a close resemblance to the annealing of 1-MeV electron...