ABSTRACT

Our novel findings concerning the spectroscopy of the Fermi edge states in pseudomorphic modulation-doped AlGaAs/InGaAs/GaAs heterostructures are as follows: i) The temperature behaviour of the E11 transition provides unequivocal evidence of the FES presence for then= 2 electron subband. The E11 peak amplitude falls abruptly down under the temperature increase within the range of 20 K. Then it becomes weakly temperature dependent up to the temperature T = 80 K; ii) The large strength of the additional feature is observed even at the lowest temperatures. It can not be of impurity nature while the doping level in the AlGaAs supplier layer is held constant under variation of the InGaAs QW width; iii) The strength of additional PL feature is strongly dependent on the n = 2 subband filling. The 2DEG concentration was derived from the low temperature Hall measurements; iv) The high stability of the feature under the temperature and excitation density elevation allows to evaluate the binding energy. It is about of7 meV; v) The A feature reveals the non-monotonous temperature and excitation density behaviour, non-typical to the well-known FES manifestations.