Difference in the nonlinear optical response of epitaxial Si on Ge(100) grown from SiH4 at 500 °C and from Si3H8 at 350 °C due to segregation of Ge

The properties of epitaxial strained Si on Ge (001) grown from SiH4 at 500 °C and from Si3H8 at 350 °C have been investigated as a function of film thickness using second harmonic generation (SHG). A clear difference in the corresponding signal amplitude, for both the interface and the “bulk” contributions, is observed. After analysis of the nonlinear susceptibility tensor components, this difference is attributed to the segregation of Ge to the SiO2/Si interface. It is demonstrated that when employed in combination with more standard experimental techniques, SHG can be a valuable tool for probing and characterizing the SiO2/Si/Ge interfaces.