Effects of initial silicon carbide surface composition on room temperature Au/β-SiC(001) interface formation

Au was deposited in situ on β-SiC(001) surfaces at room temperature after the substrates were cleaned by annealing, first in a Si flux and then in vacuum. By adjusting the time and temperature of the vacuum anneal, SiC surfaces of four compositions, ranging from Si-rich to Si-deficient, were obtained. Surfaces were monitored using Auger electron, electron energy loss, X-ray photoelectron, and ultraviolet photoelectron spectroscopies as Au films ranging in thickness from ∼ 1 to 37 Å were deposited. For Au on Si-terminated β-SiC surfaces, three distinct regions formed as the Au overlayer grew: interfacial Au-Si alloy, pure Au above the alloy, and a surface layer of Au-Si alloy. Interfacial alloy thickness and surface alloy Si concentration were both proportional to the amount of Si on the initial SiC surface. For Au depositions š 5 Å, bands bending change, dependent on the initial β-SiC surface composition, were observed. On Si-deficient β-SiC surfaces, the Au growth mode differed completely. Au clusters formed, similar to Au behavior on C substrates. No band bending changes were observed, consistent with weak film/substrate interaction. For the Au/β-SiC system, overlayer composition and morphology are controlled by composition changes in the top 1-2 monolayers of the SiC substrate.