Optical properties of ZnO-based step quantum wells

摘要

The Mg_xZn_(1-x)O/ZnO and Mg_xZn_(1-x)O/Cd_yZn_(1-y)O step quantum well structures have been produced by the pulsed laser deposition method. It has been established that the increase of the barrier height ratio for charge carriers in the conduction and valence bands upon transition from the active ZnO layers in the Mg_xZn_(1-x)O/ZnO system to the active layers of Cd_yZn_(1-y)O in a low-dimensional Mg_xZn_(1-x)O/Cd_yZn_(1-y)O system is associated with the fact that the electron concentration in Cd_yZn_(1-y)O films rises with an increase in the cadmium content. As the result, the Fermi level is displaced to the bottom of the conduction band. In the range of quantum well widths from 1 to 12 nm the nonmonotonous growth of exciton and defect-related intensities in photoluminescence spectra is observed.