Real-time x-ray scattering study of surface morphology evolution during ion erosion and epitaxial growth of Au(111)

We describe a detailed real-time x-ray scattering study of the evolution of the surface morphology of Au(111) both during ion erosion with 500-eV Arions, and during homoepitaxial growth. We monitor the erosion and growth mo rphologies as a function of substrate temperature. We also monitor the surf ace reconstruction, since it is known to play an important role in determin ing growth regimes on Pt( ill). Ion irradiation of Au(111) leads to surface morphology evolution by step retraction above 270 degrees C and quasi-laye r-by-layer removal at 90-220 degrees C. The extent of the surface reconstru ction on Au(111) during ion irradiation gradually decreases with decreasing temperature. While the herringbone reconstruction remains during ion irrad iation at 270 degrees C, the long range order is lost and only the (22X roo t 3) reconstruction is present at 170 degrees C. We also observe layer-by-l ayer growth in the Au/Au(111) system at 55-145 degrees C, a result that dif fers from the usual behavior of homoepitaxy on fcc(111) surfaces. As in the layer-by-layer erosion regime, only the (22X root 3) reconstruction is pre sent during layer-by-layer growth. Room temperature ion irradiation leads t o a (1X1) surface structure and a three-dimensional rough morphology exhibi ting pattern formation with a characteristic lateral length scale. Line-sha pe analysis of the diffuse scattering in transverse x-ray scans taken durin g low temperature ion irradiation, indicates that the characteristic latera l length scale increases with time consistent with a power law l similar to t(0.28). This agrees with a simple analysis of the position of the satelli te peak in the diffuse scattering in these transverse x-ray scans. [S0163-1 829(99)10647-7].