CHARACTERIZATION OF THE LINEAR OPTICAL-PROPERTIES OF A MULTIPLE-QUANTUM-WELL STRUCTURE IN THE SHEET-MODEL APPROXIMATION

The possibility of determining the linear optical response tensor of a multiple quantum well (MQW) structure from optical reflection spectra is discussed. Taking into account local-field effects, the optical pa rameters of the MQW system are derived directly from the sheet conduct ivity tensor of the individual quantum well. For an amorphous Si/SiO2 MQW structure deposited on a crystalline Si substrate, both s- and p-p olarized reflection spectra were measured at different angles of incid ence in the near-infrared and visible frequency regions. It was shown that the s-polarized spectra can be characterized by means of only one (complex) parameter, whereas in general it is impossible to account f or the p-polarized spectra parametrically in a full range of angles of incidence even four angular independent parameters. Finally, it was d emonstrated that Feibelman's d-parameters can only be used to describe the experimental spectra at near-normal and grazing angles of inciden ce.