Method for calculating photo- and electroreflectance spectra from semiconductor heterostructures

Lineshape analysis of photoreflectance spectra from InGaAs/GaAs quantum wells

“…The weak intralayer inhomogeneities are superimposed by the generally much stronger variations of optical constants between different layers. In previous works, we developed and applied a method to calculate PR spectra from heterostructures which treats each kind of inhomogeneity in its own way [10,11]. The intralayer inhomogeneity is treated by means of a generalization of the perturbation approach, developed for the case of an infinite half space [12].…”

“…To calculate the electric field profile determining the spatial distribution of the DF changes, we assumed that the potential is constant far inside the samples and takes a certain surface value at the sample/vacuum boundary [10,11]. In the case of undoped systems, this surface potential is not determined by the surfacelocalized states' density but by the occupation of the available states by free carriers which have migrated to the surface from the MBE grown layers.…”

“…First, as they have already been published, we only discuss briefly our methods of calculation [10,11]. The problem of PR spectra calculations is the problem of the reflection coefficient calculations in the presence and in the absence of modulating light, taking into account an influence of the modulated and unmodulated built-in electric field profiles on the dielectric function ε(ω, z).…”

“…To account for the electric field induced change in the DF (z) of bulk-like GaAs layers we used the wellknown Airy function expression [10,11], following the Franz-Keldysh oscillations theory. The changes in the QW DF were described using the quantum-confined Stark effect theory and bearing in mind that we are dealing with the excitonic transitions.…”

“…To the best of our knowledge, this is the first time that rigorously calculated PR lineshapes from InGaAs/GaAs heterostructures are compared with the experimental lineshapes for a set of samples with different cap layer thicknesses. The theoretical spectra are obtained by the original hybrid matrix method, developed in our previous works [10,11]. This method enables us to rigorously calculate the PR spectra.…”