The Role of Generation Volume and Photon Recycling in "Transport Imaging" of Bulk Materials
Haegel, Nancy M.
Crooker, Peter P.
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The goal of this research was to use Monte Carlo simulations to further develop the model that describes transport imaging by including a more realistic description of the generation region created by the incident electrons. Monte Carlo simulation can be used to determine the energy distribution in bulk materials due to the interaction with incident electrons. In the simulation, the incident electrons undergo both elastic and inelastic scattering events. Through these events, the energy of the electrons is transferred to the target materials. This deposited energy can generate electron-hole pairs and then, via recombination, photons. In the experimental work, these photons are measured by a CCD camera connected to an optical microscope in a scanning electron microscope (SEM). Monte Carlo simulations were performed for a range of target materials and compared to the luminescence distributions measured experimentally. The simulated energy distributions are always spatially narrower than the optical image from the SEM. We propose possible explanations that need to be evaluated: the relationship between deposited energy and final electron distributions in the target material and photon recycling, in which locally generated photons are reabsorbed to produce a wider luminescence distribution. Further experiments are proposed to identify the limiting factors determining the minimum luminescence distribution.
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