CHARACTERIZATION OF SIGE MULTIPLE QUANTUM-WELLS BY SPECTROSCOPIC ELLIPSOMETRY AND PHOTOLUMINESCENCE

Two SiGe multiple quantum well structures that had been characterized already by double-crystal X-ray diffraction (DCXRD) have been examined by spectroscopic ellipsometry (SE) and photoluminescence (PL). Analysis of the SE measurements was based upon the nominal growth conditions rather than the DCXRD findings. This analysis was able to provide the thicknesses and compositions of the layers comprising the heterostructure easily and quickly. Moreover, the SE analysis also provided estimates of the variation in these thicknesses and compositions, as well as in the heterostructure periodicity. It was found that the SE results confirm and enhance the DCXRD findings. The interpretation of the PL spectra benefits from the SE characterization and illuminates the nature of the small uncertainties in composition and layer thickness found by SE. These results demonstrate that SE provides a quick, extensive and reliable post mortem analysis of such materials.