METHOD FOR CALCULATING PHOTOREFLECTANCE AND ELECTROREFLECTANCE SPECTRA FROM SEMICONDUCTOR HETEROSTRUCTURES

A method for calculating photo- and electroreflectance spectra from we akly inhomogeneous layers of semiconductor heterostructures is develop ed. Transfer matrices are used in order to solve the propagation of Li ght between different layers and perturbation theory in order to obtai n the transfer matrix for a single layer. If applied to an infinite ha lf space, the method reproduces the result by Aspnes and Frova [Solid State Commun. 7, 155 (1969)]. The electric held profiles of the hetero structures are calculated by means of an integral equation which holds under quite general conditions including incomplete dopant ionization and carrier degeneracy. The application of the general theory is demo nstrated by calculating photoreflectance spectra of homogeneously n-do ped semi-infinite GaAs samples with different doping levels, and of a (Al,Ga)As heterostructure with an interface charge between buffer laye r and substrate. Due to its speed and accuracy the method has the pote ntial for an on-line simulation of photo- and electroreflectance spect ra.