Unusual Band-Edge Photoluminescence Intensity Emitted by Cu-Diffused Silicon Crystals

概要

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Band-edge photoluminescence (BDE-PL) intensities of Czochralski (Cz) and float-zone (FZ)-grown silicon crystals diffused with Cu were observed from room temperature (RT) to 4.2 K. In contrast to the behavior of ordinary transition metals, unexpected enhancements of the BDE-PL intensities of both Cz and FZ samples were observed at RT in an appropriate Cu concentration range. For the observation temperature of 77 K, however, while the BDE-PL intensity of the Cz sample increased following the same trend as that observed at RT, the intensity of the FZ sample abruptly decreased given the same Cu concentration range as that of the Cz sample. The marked difference in the BDE-PL intensities between Cz and FZ samples was also observed with the change in the diffusion temperature of Cu. These unusual BDE-PL intensities were well explained on the basis of two competitive actions of Cu: the intensity enhancement due to surface passivation by Cu and the intensity reduction caused by a deep-level Cu center formed in the bulk.
2010-06-25