HETEROEPITAXY OF COPPER ON SAPPHIRE UNDER UHV CONDITIONS

In a uhv system, with a base pressure below 10(-10) mbar Cu films on c-cut sapphire (Al2O3) have been grown by e-gun evaporation. The films were characterized by X-ray diffraction, in situ RHEED, SEM and Talystep profilometer. Pole figures taken with a diffractometer show sharp peaks in the phi-plane, revealing epitaxy. The halfwidths in phi and chi depend strongly on the polishing method by which the substrates have been prepared and on the substrate temperature during evaporation. With Aerosil polished substrates the epitaxy temperature is as low as 120-degrees-C and even at room temperature moderate epitaxy can be achieved. Diamond polished substrates show epitaxy only for T(S) > 200-degrees-C.