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The cathodoluminescence technique (CL) performed in the Scanning Electron Microscope (SEM) offers opto-electronic characterisation of some nanostructures and it is a powerful tool for studying the compositional variation or band structure of three-dimensional microscale or nanoscale construction. The major problem of the CL technique is the high spatial resolution concerning the low-dimensional structure. In the present paper a Monte Carlo calculation model of AlAs/GaAs/AlAs nano structure is presented in order to describe the influence of different parameters such as the thickness of quantum well and barrier as well as the diffusion length. The carrier excess generated during the collision of the incident electron with the atoms of the material (random walk) is calculated as a function of depth taking into account the confinement phenomenon within the quantum well. The radiative recombination of electron-hole pairs is collected as a light (CL signal). Numerical results obtained for three quantum wells (60, 30 and 10 nm) are compared with experimental data. |