INTERFACIAL ROUGHNESS SCALING AND STRAIN IN LATTICE-MISMATCHED SI0.4GE0.6 THIN-FILMS ON SI

Interfacial roughness parameters and lattice strain of Si0.4Ge0.6 film s with varying thickness epitaxially grown on Si(100) were determined using the techniques of grazing-incidence x-ray scattering and diffrac tion. The roughness of both the buried interface and sample surface fo llows a similar power-law scaring behavior with an exponent beta aroun d 0.71 for films below the critical thickness, and it undergoes a larg e change above the critical thickness. Observation of such a scaling l aw thus establishes a quantitative correlation between the interfacial roughness and lattice strain, and also allows the prediction of inter facial roughness as a function of film thickness of this compound. (C) 1995 American Institute of Physics.