SCALING OF SURFACE-ROUGHNESS IN A HETEROGENEOUS FILM GROWTH SYSTEM - GEXSI1-X ON SI

We examine how the roughness of compositionally graded, relaxed GeSi/S i(001) films can be understood in terms of theoretical ideas based on continuum descriptions of surface growth. The roughness of all samples shows a universal behavior: it increases linearly with length at smal l length scales and becomes constant at large length scales. Remarkabl y, all data can be collapsed onto one universal can e. These results c an be described by a linear model composed of Laplacian and surface di ffusion terms. We also examine the nonuniversal amplitudes and the up- down symmetry to investigate rigorously the linearity of the model.