Investigation of photoconductivity of individual InAs/GaAs(001) quantum dots by Scanning Near-field Optical Microscopy

The spatial distribution of the photocurrent in the input window plane of a GaAs-based p?i?n photodiode with embedded self-assembled InAs quantum dots (QDs) has been studied with the photoexcitation through a Scanning Near-field Optical Microscope (SNOM) probe at the emission wavelength greater than the intrinsic absorption edge of the host material (GaAs). The inhomogeneities related to the interband absorption in the individual InAs/GaAs(001) QDs have been observed in the photocurrent SNOM images. Thus, the possibility of imaging the individual InAs/GaAs(001) QDs in the photocurrent SNOM images with the lateral spatial resolution ~ 100 nm (of the same order of magnitude as the SNOM probe aperture size) has been demonstrated.