Energy transport studies using spatially resolved luminescence

A method is described in which a small and well-defined area on the face of a crystal is illuminated by a focused laser beam and the light emitted from adjoining areas is spatially analyzed. Our experimental studies, done on nitrogen-doped III-V semiconductors, show that spatial distribution of a Raman spectral line properly monitors the illumination spot geometry as well as the instrumental response. It is shown that the zero phonon line associated to the nitrogen-trapped exciton and the corresponding phonon replica exhibit different spatial distributions. The effect of temperature on the spatial distribution of light emitted both by a zero phonon process and its phonon replica is examined. These results are discussed in terms of possible implications for the energy transfer process.