X-RAY-DIFFRACTION STUDY OF A SEMICONDUCTOR ELECTROLYTE INTERFACE - N-GAAS(001)/H2SO4(CU)/

We used X-ray diffraction to investigate the n-GaAs(001)/0.5M H2SO4 in terface in-situ under potential control in a three-electrode, thin-lay er electrochemical cell. The intensity of crystal truncation rods as a function of the electrode potential was recorded. A pronounced increa se in surface roughness was proven by the strong decrease in the rod i ntensities with time at an electrode potential of -0.6 V versus SCE. S urprisingly, this process could be partially reversed at more negative potentials (< -0.9 V versus SCE). Possible mechanisms explaining thes e observations are discussed. After the deposition of Cu from a 0.5M H 2SO4/1mM CuSO4 solution, three-dimensional, epitaxially grown Cu islan ds with several degree mosaic spread were observed.