LINEAR AND NONLINEAR OPTICS OF WIDE-GAP II-VI SEMICONDUCTORS

The purpose of this contribution is to review some of the present acti vities in II-VI semiconductor research at this institute. In the field of bulk materials, the IR spectra of ZnO:Ga are presented with electr on densities up to 2 x 10(20) cm(-3). The density dependence of the pl asmon-phonon mixed states is given. In alloy semiconductors we investi gate the temperature dependence of the absolute external luminescence yield, which reaches values close to unity for selected CdS1-xSex samp les. Furthermore the incoherent population dynamics below and above la ser threshold is measured, including the observation of self pulsation in the stimulated output. The investigation of the dynamics and of th e excitation spectra of the luminescence of CdS and of ZnSe bayed quan tum wells gives information about the relaxation process and the coupl ing to (barrier) LO phonon modes. The slow thermalization of hot free excitons in ZnSe QWs is observed directly in time-resolved luminescenc e in the phonon-sideband region. For CdSe quantum dots in a glass matr ix, data of the exchange splitting and the coupling to quantized acous tic phonons are given as a function of the dot radius. CdS quantum dot s with organic cladding layers and high volume fraction show between I TO and Ag contacts an electroluminescence which can be tuned by the ap plied voltage through the whole visible spectrum.