INTERSUBBAND RELAXATION RATES OF A 2-DIMENSIONAL ELECTRON-GAS UNDER HIGH MAGNETIC-FIELDS

The electron-bound hole luminescence of a GaAs-based heterojunction ha s been investigated as a function of magnetic fields at low temperatur es. The study of the intensities originating from different Landau lev els allows one to obtain precious information about the relaxation rat es within these levels and provides values far above those predicted b y standard theories. A new mechanism involving impurity-assisted phono n emission is proposed which gives good agreement with the experimenta l results.