DETERMINATION OF THE INTERFACIAL ROUGHNESS EXPONENT IN RARE-EARTH SUPERLATTICES

The interfacial roughness in Ho/Y and Ho/Lu superlattices has been stu died using high-resolution x-ray diffraction. The transverse width of the superlattice Bragg peaks broadens almost linearly as a function of the component of the reduced wave vector parallel to the growth direc tion, while the line shape is invariant, and is described by a Lorentz ian raised to the power of approximate to 5/2. These results are inter preted as a signature of conformally rough interfaces, and the roughne ss exponent is determined to be alpha = 0.85 +/- 0.05. It is also show n how alpha may be altered by adjusting the growth conditions.