ELECTROMODULATION SPECTROSCOPY OF AN ARRAY OF MODULATION-DOPED GAAS GA1-XALXAS QUANTUM DOTS - EXPERIMENT AND THEORY/

A recent photoreflectance (PR) experiment on a GaAs/Ga1-xAlxAs modulat ion-doped quantum dot array shows that at 77 K the quasi-two-dimension al ''2C-2H'' interband transition develops a series of evenly spaced o scillations. Such features are due to the quantization of the energy l evels related to the in-plane paraboliclike potential for such reduced -dimensional systems, e.g., evenly spaced conduction and valence subba nds. However, for the other dominant feature, i.e.,''1C-1H''/''1C-1L,' ' no fine structure is observed since the first electron subband is oc cupied. We present a self-consistent field theory and numerical calcul ations for the intersubband absorption coefficient of an array of GaAs /Ga1-xAlxAs quantum dots with lateral parabolic confining potentials f or electrons and holes. Our numerical results for the derivative of th e absorption coefficient have features which are quite similar to thos e observed in the PR experiment.