Modelling the Optical and Vibrational Properties of the Si (100) Surface

Speaker: Robert Minnings (MCSC)

Abstract: In the presentation I will discuss a correlation between the structural, dynamical, electronic and optical properties of the clean Si(100) surface, we investigated theoretically. Si(100) surface is the cornerstone of the modern microelectronics and it has been extensively investigated theoretically and experimentally. It offers very interesting nonlinear dynamics due to dimer, the main Si(100) structural element, flipping. Its detailed understanding can provide noninvasive access to the microscopic surface processes through Si(100) vibrational and optical spectroscopy. Even though a wide range of temperatures were used in experimental characterization, most of the structural and optical properties of Si(100) were previously calculated at absolute zero. One of the authors (A.I.S.) has developed and applied a formalism for temperature dependent dielectric functions of bulk semiconductors and compared with the experimental measurements for GaAs and Si bulk [Z. A. Ibrahim, A. I. Shkrebtii, et al., Phys. Rev. B 77, 125218 (2008)]. At semiconductor surfaces, however, temperature modification of the atomic vibration and the optical response should be even more pronounced than for the bulk due to surface atom reduced coordination, symmetry change, reconstruction. We apply the above computational approach to Si(100). I will start by discussing the foundations of the numerical formalism used, then finish with some results from the first principles modelling of the Si(100) surface Dynamical and Optical properties, using the Quantum Espresso Software package.