Quantum confinement in Si and Ge nanostructures: Effect of crystallinity

  1. Get@NRC: Quantum confinement in Si and Ge nanostructures: Effect of crystallinity (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1117/12.2036323
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Proceedings titleSPIE - International Society for Optical Engineering. Proceedings
ConferencePhotonics North 2013 Conference, 3 June 2013 through 5 June 2013, Ottawa, ON
Article number891515
SubjectConfinement effects; Confinement potential; Crystallinities; Effective mass; Effective-mass theory; Experimental parameters; Oscillator strengths; Position-dependent effective mass; Amorphous materials; Germanium; Interface states; Nanostructures; Photonics; Quantum confinement; Semiconducting germanium; Silicon
AbstractWe look at the relationship between the preparation method of Si and Ge nanostructures (NSs) and the structural, electronic, and optical properties in terms of quantum confinement (QC). QC in NSs causes a blue shift of the gap energy with decreasing NS dimension. Directly measuring the effect of QC is complicated by additional parameters, such as stress, interface and defect states. In addition, differences in NS preparation lead to differences in the relevant parameter set. A relatively simple model of QC, using a 'particle-in-a-box'-type perturbation to the effective mass theory, was applied to Si and Ge quantum wells, wires and dots across a variety of preparation methods. The choice of the model was made in order to distinguish contributions that are solely due to the effects of QC, where the only varied experimental parameter was the crystallinity. It was found that the hole becomes de-localized in the case of amorphous materials, which leads to stronger confinement effects. The origin of this result was partly attributed to differences in the effective mass between the amorphous and crystalline NS as well as between the electron and hole. Corrections to our QC model take into account a position dependent effective mass. This term includes an inverse length scale dependent on the displacement from the origin. Thus, when the deBroglie wavelength or the Bohr radius of the carriers is on the order of the dimension of the NS the carriers 'feel' the confinement potential altering their effective mass. Furthermore, it was found that certain interface states (Si-O-Si) act to pin the hole state, thus reducing the oscillator strength. © 2013 SPIE.
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AffiliationMeasurement Science and Standards; National Research Council Canada
Peer reviewedYes
NPARC number21270954
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Record identifier71f2cb9a-8f25-4916-9023-8ee2a9d0c077
Record created2014-02-18
Record modified2017-04-24
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