Transport Imaging developing an optical technique to characterize bulk semiconductor materials for next generation radiation detectors
Catalano, Sarah L.
Haegel, Nancy M.
Smith, Craig F.
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Characterization of the mobility-lifetime product is critical to the development of new materials for semiconductor radiation detectors. An optical technique has been developed that allows for the direct determination of the minority carrier diffusion length, drift length, and mobility-lifetime product from a single image of the recombination luminescence in semiconductor materials. Excess carriers are generated using the electron beam in a scanning electron microscope. The charge is then drifted by applying an electric field, and the subsequent recombination luminescence is imaged by an optical microscope on a high-sensitivity CCD camera. The challenge in applying this technique to new materials for nuclear radiation detectors is the requirement for thick samples and the resultant need to characterize transport in three dimensions. In this work, initial research was performed on the simulations and analysis of experimental data required to characterize thick layers of high purity GaAs for nuclear radiation detectors. The first models were applied to extract values for surface recombination velocity, which plays a key role in determining the excess carrier distribution in bulk materials. Cathodoluminescence of one promising high Z material, BiFeO3, is performed.
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