PHOTOVOLTAIC SPECTROSCOPY OF EXCITON STRUCTURES IN ZN1-XCDXSE ZNSE MULTIPLE-QUANTUM WELLS/

Exciton transitions in photovoltaic spectra of strained-layer multiple -quantum-well samples of Zn1-xCdxSe/ZnSe grown by molecular-beam epita xy were observed up to room temperature. Quantum level energies were c alculated by means of the envelope-function method including strain, G reat care was taken in order to evaluate the band offsets, the band-ga p dependence on temperature and alloy concentration, as well as the qu antum confinement enhancement of the exciton binding energies. Very go od agreement between experimental and calculated values of the exciton energy position was found in the 80-300 K temperature range. Calculat ed binding energies as high as 35-40 meV account for the occurrence of the exciton structures up to 300 K. (C) 1996 American Institute of Ph ysics.