| Abstract: | We report undulation spectra in acceptor doped ZnTe and InP. The strong increase in exciton localisation energy in the presence of a second neutral acceptor produces a perturbation in transition energy much larger than that from the background electric field due to compensated acceptors. We suggest that the undulations arise from fluctuations in the intensity of luminescence at relatively close pairs due to quasi-regular smooth variations in the envelope of the density of available pair states as a function of pair separation and therefore transition energy. The form of the intensity distribution in the low temperature spectra and its dramatic evolution with temperature can be explained by phonon-assisted tunneling transfer. Anti-Stokes phonon assisted tunneling between well localised exciton states at close acceptor pairs and extended states at acceptors in average concentration environments above the threshold for Anderson delocalisation is responsible for the change in spectral form at higher temperature. |
