OPTICAL-PROPERTIES OF AMORPHOUS SI PARTIALLY CRYSTALLIZED BY THERMAL ANNEALING

Spectroscopic ellipsometry (SE) has been used to study optical properties of amorphous (a-) Si partially crystallized by thermal annealing. The a-Si samples used were prepared by rf sputtering on (100)Si. A linear regression analysis (LRA) and a Bruggeman effective-medium approximation (EM A) indicate that the annealed layer consists of volume fractions of a-Si and microcrystalline (muc-) Si. Isothermal annealing experiments at 1100-degrees-C suggest that the crystallization starts to occur very quickly (less-than-or-equal-to 30 min) and then slows with an increase in the annealing time. The complex dielectric functions of muc-Si deduced here differ appreciably from that of crystalline (c-) Si, especially in the vicinity of the sharp critical-point (CP) features. Analyses are also presented on the dielectric-function spectra of muc-Si using a simplified model of the interband transitions.