EFFECTS OF THE SUBSTRATE POTENTIAL ON THE INCORPORATION MANNER OF HYDROGEN AND IMPURITY IN a-Si : H FILMS S. Hotta, Y. Tawada, H. Okamoto and Y. Hamakawa J. Phys. Colloques, 42 C4 (1981) C4-631-C4-634 DOI: 10.1051/jphyscol:19814138