G. Pistone

Microscopic quantum theory of spatially resolved photoluminescence in semiconductor quantum structures

We present a microscopic analysis of spatially resolved photoluminescence and photoluminescence excitation spectroscopy in semiconductor quantum structures. Such theoretical and numerical framework provides a general basis for the description of spectroscopic imaging in which the excitation and detection energies and spatial positions can all independently be scanned. The numerical results clarify the impact of the near-field optical setup on the obtained images and resolutions.

Spatially resolved photoluminescence in quantum wells with interface roughness: a theoretical description

We present a microscopic theoretical description of spatially resolved photoluminescence in GaAs quantum wells with interface roughness. The theory derives the kinetic equations using the excitonic wavefunctions obtained by solving numerically the effective Schrodinger equation for the excitonic centre of mass motion in the presence of disorder. The kinetic equations describe acoustic phonon scattering, radiative decay, and inhomogeneous sample excitation and/or light detection. The influence of disorder, temperature, and spatial resolution on the image formation is analysed with emphasis on the role of different interface textures. In particular, we consider two samples characterized by effective disorder potentials with different correlation lengths. Numerically calculated two-dimensional images agree with images from spatially resolved photoluminescence experiments and put forward the potential of the method for the understanding of near-field light emission from semiconductor quantum structures.

Microscopic theory of spatially resolved photoluminescence in quantum structures

We present a microscopic quantum theory of spatially resolved photoluminescence in quantum wells with interface fluctuations. The theory can model low-temperature photoluminescence and photoluminescence excitation experiments performed in illumination, collection, illumination–collection mode or diffusion experiments where the spatial positions of excitation and collection are scanned independently. Numerically calculated two-dimensional images clarify the impact of the microscope setup on the obtained images and resolutions.

Near-field light emission from dark states excitonic occupations

We theoretically analyze the carrier capture and distribution among the available energy levels of a symmetric semiconductor quantum dot under continuous-wave excitation resonant with the barrier energy levels. At low temperature, all the dot level occupations but one monotonically decrease with energy. The uncovered exception, corresponding to the second (dark) energy level, displays a carrier density exceeding that of the lowest level by more than a factor two. The root cause is not radiative recombination before relaxation, but instead, carrier trapping due to the symmetry-induced suppression of radiative recombination. Such a behavior can be observed by collection-mode near-field optical microscopy.

Quantum theory of spatially resolved photoluminescence in semiconductor quantum wells

We present a microscopic quantum theory of spatially resolved photoluminescence in quantum structures with interface fluctuations that includes light quantization, acustic phonon scattering, and inhomogeneous sample‐excitation and/or light‐detection. The obtained numerically calculated images agree with images from near‐field photoluminescence experiments and put forward the potentials of the method for the understanding of near‐field light emission from semiconductor quantum structures.