DETERMINATION OF INTERFACE LAYER STRAIN OF SI SIO2 INTERFACES BY REFLECTANCE DIFFERENCE SPECTROSCOPY/

Detailed studies of the often-observed resonance feature near 3.4 eV i n the reflectance difference spectrum of Si/SiO2 interfaces and Si sur faces show that the resonance is due to the intrinsic local-field effe ct, and that its energy position coincides with the E-1 energy of bulk Si. Using the energy position of the resonance of the pseudomorphical ly grown Si/CaF2 interfaces as a reference point, the strain-induced r esonance energy shift of the Si interface layer at several Si/SiO2 int erfaces are obtained and the strain in these layers is determined. The results show that the interface layers are highly strained with an eq uivalent hydrostatic pressure of 0.79 GPa, but still maintain a high d egree of order. (C) 1997 American Institute of Physics.