In situ specular and diffuse x-ray reflectivity study of growth dynamics in quench-condensed xenon films

Specular and diffuse reflectivity and diffraction of x rays are used to pro be polycrystalline films of xenon quench condensed onto a SiO2/Si substrate . Measurements during deposition complement more extensive static measureme nts. Stable nonequilibrium structures are observed. We interpret our observ ations in terms of island growth and coalescence. Island separation and ult imate size are strongly temperature dependent. Coalescence has a pronounced effect at the lowest temperature studied (17 K) where islands are small an d have large surface-to-volume ratios. We observe a concurrent increase in roughness and reduction in diffuse scattering, indicating a change in surfa ce morphology. Continued deposition yields a highly disordered, porous stru cture on top of the dense coalesced layer. At 25 and 35 K bulk density film s grow with a surface morphology that evolves only slowly from that determi ned before coalescence. Bulk diffusion allows intermixing and prevents a co mposite film structure like that observed at lower temperatures. [S0163-182 9(99)06404-8].