Growth characteristics and surface roughening of vapor-deposited MgO thin films

Abstract

Highly (100)-oriented magnesium oxide (MgO) crystalline thin films were grown on Si, GaAs, and fused quartz substrates by an aerosol-assisted chemical vapor deposition using magnesium ethoxide as a source material. Structures of the substrates had little influence on the growth orientation of MgO films indicating that the growth orientation of the films is determined by the lowest surface energy of the crystal structure. Surface morphology of the films investigated by atomic force microscope as a function of the films thickness showed that the formation of three-dimensional islands dominates the initial stage of the film growth. Surface roughness exponent $\ensuremath{\alpha}$ was determined to be about 0.87 for all the MgO films grown on Si and GaAs. The result agrees approximately with the diffusion dominant model of kinetic roughening. Kinetic limitations play an important role in determining surface morphology of MgO/semiconductors that is qualitatively governed by near equilibrium growth mode of Volmer-Weber or Stranski-Krastanov.