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Effect of Stress and Interface defects on Photo Luminescence of Si nano-crystals embedded in SiO2

Shenoy, Bhamy Maithry and Hegde, GM and Mahapatra, Roy D (2013) Effect of Stress and Interface defects on Photo Luminescence of Si nano-crystals embedded in SiO2. In: 2nd Conference of the Optics-and-Photonics-Society-of-Singapore / International Conference on Optics in Precision Engineering and Nanotechnology (icOPEN), APR 09-11, 2013, Singapore, SINGAPORE.

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Official URL: http://dx.doi.org/10.1117/12.2020489


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.

Item Type: Conference Paper
Series.: Proceedings of SPIE
Publisher: SPIE-International Society for Optical Engineering
Additional Information: Copyright of this article belongs to SPIE-International Society for Optical Engineering.
Keywords: Photoluminescence; Band Structure; Si Nano-Crystal; Molecular Dynamics; Strain; Interfacial Stress
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited: 22 Oct 2013 12:14
Last Modified: 22 Oct 2013 12:14
URI: http://eprints.iisc.ac.in/id/eprint/47557

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