Effects of annealing on type converted Si and space solar cells irradiatedwith heavy fluence 1 MeV electrons

We present a detailed quantitative study of the thermal annealing character istics of deep level defects in Si and space solar cells with boron-doped p -Si base layer, introduced by 1 MeV electrons irradiation. Present isochron al annealing provides an overall different annealing behavior of the defect s in type converted (n-type) heavy dose electrons (phi = 1 x 10(17) e/cm(2) ) irradiated samples, contrary to earlier low dose electrons studies. Isoch ronal annealing provides evidence that the minority carrier trap (Ec - 0.18 eV) and majority carrier trap (Ec - 0.71eV) that appear after type convers ion play a dominant role in carrier removal and are the major defects respo nsible for the type conversion as well as the severe degradation of space s olar cells. This study also sheds light on the fact that heavy electron irr adiation not only changes the structure of the device (p to n-type) but als o makes the defect structure more complex as compared to simple defects str ucture in low dose samples.