ИСТИНА

We investigated the quantum size effect, as applied to electronic structure of ultra-thin narrow-band semiconducting layers and multilayers by picosecond biharmonic pumping (BP) technique and photoelectron spectroscopy (PS) and shown that the quantum size renormalization of the electronic structure is accompanied by sufficient transformation of the self-diffraction efficiency as a function of BP frequency detuning. We found one- and two- photon resonances related to the electron transitions between different renormalized sub-bands in the experimental dependence. In addition, we studied the peculiarities of the self-diffraction in quantum size narrow-band semiconducting structures by picosecond BP and PS including kinetics of relaxation processes. On this basis, we developed an original model of such films’ nonlinear response which enabled us explain the experimental data. The values of energy shift and splitting for each type of bands as well as characteristic times of the relaxation processes were determined.