Modelling of photoreflectance phenomena in layered media

Abstract

This paper presents a detailed three-dimensional analysis for the modelling of the photoreflectance effect, in particular the response of layered samples is considered. The dependence of t h e photoreflectance signal on various parameters such as lifetime, surface recombination velocity and carrier diffusion coefficient is discussed. It is shown that the carrier diffusion coefficient and the thermal diffusivity play an important role in determining the signal level from the photoreflectance system. The effects of the wavelength of the pump and probe beams are also discussed. Furthermore, a fast numerical algorithm, allowing for a rapid computational evaluation, has been applied.

Enhanced photothermal displacement spectroscopy for thin-film characterization using a Fabry-Perot resonator

“…This has been done in a variety of contexts, [33][34][35][36][37] but the form of the solutions is somewhat involved, and fitting them to experimental data to extract a sample's thermal properties, especially those of a sample that includes a thin, inhomogeneous surface layer, is computationally intensive.…”

“…A rigorous modeling of the photothermal response requires a complete, multidimensional solution to the diffusion equation to solve for the temperature distribution inside the sample, then a solution to the Navier-Stokes equations to solve for the resulting thermal expansion. This has been done in a variety of contexts [33,34,35,36,37], but the form of the solutions is somewhat involved, and fitting them to experimental data to extract a sample's thermal properties, especially those of a sample that includes a thin, inhomogeneous surface layer, is computationally intensive.…”

Far field resolution beyond the Abbe limit using photodiffraction

“…For a material such as a semiconductor the change in sample reflectivity will depend not only on the temperature rise but also on the excess photocarrier concentration, in which case θ(ξ) becomes a more complicated hybrid term. The underlying physics behind these effects is described in Liu et al . (1993).…”

“…An object may be ‘weak’ from the point of view of conventional reflectance but ‘strong’ from the photoreflectance point of view. An important example of such a case is ion‐implanted silicon, where the reflectivity variation is small but the photoreflectance change from, say, crystalline to amorphous silicon is more than two orders of magnitude (Liu et al ., 1993).…”

Thermomechanical study of AlCu based interconnect under pulsed thermoelectric excitation

“…15,[20][21][22][23] In these techniques a high power laser excites the material at a given point, producing in the neighborhood different effects such as heating and deformation, generation of plasma waves and acoustic waves, etc. These effects modify the parameters ͑intensity, phase, propagation, direction, etc.͒ of another laser light ͑usually from a low power He-Ne laser͒ reflected upon the excited zone.…”