EXISTENCE OF IRREVERSIBILITY IN STAEBLER-WRONSKI EFFECT AND FATIGUE EFFECT OF PHOTOLUMINESCENCE OF GDa-Si : H S. Nitta, Y. Takahashi and M. Noda J. Phys. Colloques, 42 C4 (1981) C4-403-C4-406 DOI: 10.1051/jphyscol:1981487