Effects of gallium impurity on radiation-resistance of Si single crystal space solar cells

Using DLTS (deep level transient spectroscopy) and in particular minority-carrier lifetime measurements, we have studied the effect of Ga impurities upon defect generation and annealing behavior of radiation-induced defects, and carrier removal and minority-carrier lifetime degradation in Si single crystals irradiated with 1-MeV electrons at room temperature. It is found that compared to the B impurity in p-type Si, the Ga impurity strongly suppresses the generation of the E/sub C/-0.18-0.21 eV defect center under irradiation. This defect in particular plays a dominant role in carrier removal as a deep donor state. In addition, the Ga impurity is found to suppress the generation of the E/sub v/+0.36 eV defect center, which is thought to act as a majority-carrier trapping center, and a recombination center. The effectiveness of the Ga impurity for suppressing the carrier removal effect is shown in comparison to the B impurity.