GROWTH AND STABILITY OF ULTRA-THIN ALUMINUM FILMS ON AG(110) AND AG(111)

The deposition of Al on Ag(110) and Ag(111) and the stability of the resulting structures have been studied by a variety of techniques. At 300 K the AES, YPS and UPS data show that initial interaction leads to formation of an interfacial compound, probably Ag2Al. This material gives rise to a characteristic Auger emission at 61 eV, assigned to an Al/Ag cross-transition, a conclusion which is supported by the XPS data. The interfacial alloy is formed with essentially equal facility on both the (110) and (111) surfaces. In the case of the (110) surface DELTAphi measurements suggest that initial Al adsorption occurs in the troughs. On both (110) and (111) surfaces, subsequent Al film growth proceeds by the Frank-van der Merwe mechanism. Thermal treatment causes rapid inward diffusion of overlayer Al for T greater than or similar to 350 K whereas the interfacial alloy is more stable and does not decompose until T greater than or similar to 450 K.