Neutron damage and annealing studies of copper-doped silicon solar cells

Abstract

The effects of Cu-doping, oxygen and dopant on the fast neutron radiation damage of silicon solar cells are studied in this paper. The diffusion length damage coefficientKL is defined as KL= (1/Li2 − 1/Lo2)φ−1= Δ(1/L2)φ−1. The Δ(1/L2) values of n/p-type cells, measured at 300 and 80K, are smaller by about one order in magnitude than those of p/n-type cells. Characteristic curves of Δ(1/L2) values versus total neutron flux of p/n, n/p and copper-doped n/p-type cells begin to deviate from a 45° straight line around a total neutron flux of 1012 to 1013 n cm−2. The effect of copper-doping on the radiation resistant property is observed with high resistivity bulk n/p-type (20 to 40 Ω-cm) cells, but not with low resistivity bulk n/p-type (10 Ω-cm) cells at 300K. Values of Δ(1/L2) versus neutron flux, measured at 80K, are not affected by copper-doping, bulk dopant and oxygen concentration in the bulk region of n/p-type cells. The isochronal annealing of silicon solar cells depends on the total neutron flux, copper-doping and carrier injection during the annealing process. Namely, copper-doping and carrier injection enhance the annealing process of the neutron-induced defect clusters in n/p-type cells.