Optical second harmonic spectroscopy of semiconductor surfaces: advances in microscopic understanding

Abstract

Even-order non-linear optical spectroscopy has emerged as an unusually sensitive technique for noninvasive analysis of surfaces and buried interfaces of centrosymmetric materials. The forefront challenges are: to develop reliable microscopic computational methods for calculating and interpreting measured surface non-linear spectra; to relate non-linear surface spectra quantitatively to linear optical surface probes such as reflectance-difference spectroscopy (RDS); and to develop convenient methods for acquiring nonlinear optical spectra over bandwidths (several electron-volts) that encompass multiple electronic surface resonances. We review recent advances in both calculation and measurement of non-linear spectra, with emphasis on reconstructed and adsorbate-covered silicon surfaces in epitaxial growth environments.

Optical Second Harmonic Generation in Semiconductor Nanostructures

“…External electric field (if present), E DC , breaks the central symmetry thus inducing the SHG and higher evenorder nonlinear response. For example, in bulk Si (and other cubic solids having inversion symmetry) only the two last terms in (2) contribute to the SHG resulting in a very weak signal [3].…”

“…In recent decades, optical techniques have been extensively used to study the size dependence of linear-, second-, and third-order optical nonlinearities of nanocrystals in relationship to the quantum confinement [1][2][3][4]. A remarkable progress has been achieved in studies of the effects of surfaces and interfaces in semiconductor nanostructures, nanowires, and nanoparticles (see [5] and references therein).…”

Improvedab initiocalculation of surface second-harmonic generation from Si(111)(1×1):H

“…Surface second-harmonic generation (SSHG) has been shown to be an effective, nondestructive, and noninvasive probe to study surface and interface properties [1][2][3][4][5][6][7][8][9][10]. SSHG experiments are now very cost effective and popular because they provide easy access to buried interfaces and nanostructures, and interest in these techniques continues to increase with the advent of ultrathin and bidimensional materials [11,12].…”

Second harmonic surface response of a composite

“…In particular second harmonic generation (SHG) has been established as a very powerful spectroscopy to study a wide range of physical and chemical phenomena at the surface centrosymmetric materials. [1][2][3] The surface sensitivity of SHG is due to the fact that within the dipole approximation a centrosymmetric environment does not radiate SH, while the inversion symmetry is broken at its surface, thus allowing the radiation of SH. On the experimental side, the new tunable high intensity laser systems have made SHG spectroscopy readily accessible and applicable to a wide range of systems.…”

“…On the experimental side, the new tunable high intensity laser systems have made SHG spectroscopy readily accessible and applicable to a wide range of systems. 2,3 However, the theoretical development of the field is still an ongoing subject of research. Some recent advances for the case of semiconducting and metallic systems have appeared in the literature, where the confrontation of theoretical models with experiment has succeeded, yielding correct physical interpretations for the SHG spectra.…”