SURFACE INSTABILITIES OF EPITAXIAL-FILMS ON A SUBSTRATE

The energy variation of an epitaxial film on a substrate is calculated when sinusoidal roughness appears at the surface, using die method of the surface dislocation model. The energy variation is negative beyond a critical value of wavelength which depends on the thickness of the film and on the ratio of the shear moduli of substrate and film. The kinetic of roughness development during film growing are discussed.