MAGNETOOPTICAL SPECTRUM OF DONORS IN ALXGA1-XAS AND ITS IMPLICATIONS ON THE DX-CENTER

The 1s-2p intracenter optical transitions of shallow donors in n-type AlxGa1-xAs (x=0.18 and 0.24) were investigated by far-infrared photoconductivity in magnetic fields of up to 10 T. The spectra could be well fitted by the hydrogenic effective-mass model, and were analyzed in terms of the effective mass m* and the linewidth. The result indicates (1) the inadequacy of the usual linear interpolation scheme for m*(x) and (2) the importance of alloy disorder in line broadening. No evidence was seen for the interaction of the shallow-donor ground state with the DX center, which is inconsistent with the model based on the DX center being an A1 state with small lattice relaxation. © 1990 The American Physical Society.