Optical properties of tilted II-VI superlattices: grown on vicinal surfaces - art. no. 165304

We have investigated the lowest emission state in tilted superlattices as a function of their tilt angle. The II-VI tilted superlattices, CdTe/CdxMg1- xTe and CdTe/CdxMn1-xTe, were obtained by molecular beam epitaxy on vicinal substrates misoriented by 1 degrees, which corresponds to a 186-Angstrom t errace width. The tilt sensitivity of the optical properties is shown by bo th theoretical calculations and experimental results. The one-dimensional c haracter is studied experimentally by optical spectroscopy in both excitati on regimes: continuous wave and time-resolved spectroscopy. In continuous-w ave photoluminescence spectra, an energy redshift of about 15 meV is observ ed when the superlattice is vertical. Such behavior is accounted for quanti tatively by a theoretical approach that uses a periodic modulation potentia l to describe the lateral confinement and that takes into account the inter mixing between Cd atoms and Mn (Mg) ones. In time-resolved spectroscopy, a temperature dependence of the decay time that is typical of exciton thermal ization in one-dimensional systems is observed. Both these results, the ene rgy shift and the lifetime dependence, are very sensitive to the one-dimens ional character, that is, to the tilt angle of the tilted superlattice, as calculated theoretically.