MAGNETIC FIELD DEPENDENCE OF THE PHOTO- AND DARK CONDUCTIVITY IN DOPED a-Si:H FILMS D. Weller, H. Mell, L. Schweitzer and J. Stuke J. Phys. Colloques, 42 C4 (1981) C4-143-C4-146 DOI: 10.1051/jphyscol:1981428