EXPERIMENTAL MEASUREMENTS OF THE THICKNESS DEPENDENCE OF THE IR REFLECTANCE FROM AL QUANTUM-WELLS

Room temperature measurements of the infrared (9.201 mu m) linear p-po larized reflectivity (R-p) of Al quantum wells deposited on SiO2 and S i substrates are reported for well thicknesses (d) ranging from 4 to 8 3 monolayers in steps of one monolayer. Oscillations with a slightly i ncreasing spatial period (similar to 2.6 Angstrom to similar to 3.4 An gstrom) are observed in R-p(d) in both cases. For the thicker (d > 50 Angstrom) wells, the oscillations are pronounced (for the Al/SiO2 syst em these changes are up to Delta R-p similar to 0.4 per monolayer, whi le for Al/Si, Delta R-p similar to 0.2 per monolayer). For the thinner d < 50 Angstrom wells in the Al/SiO2 system a parabolic decrease in R -p(d) is clearly seen while for the Al/Si system this feature is absen t. (C) 1997 Elsevier Science B.V.