A photoluminescence study of the donor structure in AlxGa1-xAs
A photoluminescence study at low temperatures of Si-doped AlxGa1-xAs (0<x<0.6) reveals the existence of four donor levels D1, D2, D3, D4, in order of increasing ionisation depth. The number of donor levels and the dependence of their ionisation energies on the composition parameter x accords qualitatively with theoretical expectations. D1 can be identified with the common 'shallow donor'. D2 and D3 have been reported in an earlier PL study by Dingle and co-workers (1977). The position of the D4 level suggests an identification with the DX centre. Its luminescence properties have been the subject of a previous publication.