Near-field photoluminescence imaging spectroscopy of an n-type modulation-doped quantum well with a lateral periodic potential

We describe near-field photoluminescence microscopy of an n-type GaAs/AlGaAs modulation-doped quantum well with a square mesh gate structure. The optical near-field image changed from a square array to an isolated dot array as the negative bias voltage between the mesh gate and back electrode was tuned. The correlation between the image and the calculated electron density distribution indicated that the photoluminescence signal was due to the recombination of electrons defined by the tunable field-induced potential and slowly diffusing holes.