22 June 2013 Effect of stress and interface defects on photoluminescence of Si nano-crystals embedded in SiO2
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Proceedings Volume 8769, International Conference on Optics in Precision Engineering and Nanotechnology (icOPEN2013); 87692N (2013) https://doi.org/10.1117/12.2020489
Event: International Conference on Optics in Precision Engineering and Nanotechnology (icOPEN2013), 2013, Singapore, Singapore
Abstract
Effect of stress and interface defects on photo luminescence property of a silicon nano-crystal (Si-nc) embedded in amorphous silicon dioxide (a-SiO2) are studied in this paper using a self-consistent quantum-continuum based modeling framework. Si-ncs or quantum dots show photoluminescence at room temperature. Whether its origin is due to Si-nc/a- SiO2 interface defects or quantum confinement of carriers in Si-nc is still an outstanding question. Earlier reports have shown that stresses greater than 12 GPa change the indirect energy band gap structure of bulk Si to a direct energy band gap structure. Such stresses are observed very often in nanostructures and these stresses influence the carrier confinement energy significantly. Hence, it is important to determine the effect of stress in addition to the structure of interface defects on photoluminescence property of Si-nc. In the present work, first a Si-nc embedded in a-SiO2 is constructed using molecular dynamics simulation framework considering the actual conditions they are grown so that the interface and residual stress in the structure evolves naturally during formation. We observe that the structure thus created has an interface of about 1 nm thick consisting of 41.95% of defective states mostly Sin+ (n = 0 to 3) coordination states. Further, both the Si-nc core and the embedding matrix are observed to be under a compressive strain. This residual strain field is applied in an effective mass k.p Hamiltonian formulation to determine the energy states of the carriers. The photo luminescence property computed based on the carrier confinement energy and interface energy states associated with defects will be analysed in details in the paper.
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Bhamy Maithry Shenoy, Bhamy Maithry Shenoy, G. M. Hegde, G. M. Hegde, D. Roy Mahapatra, D. Roy Mahapatra, "Effect of stress and interface defects on photoluminescence of Si nano-crystals embedded in SiO2", Proc. SPIE 8769, International Conference on Optics in Precision Engineering and Nanotechnology (icOPEN2013), 87692N (22 June 2013); doi: 10.1117/12.2020489; https://doi.org/10.1117/12.2020489
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