The effect of strain on gas–surface reactivity in group-IV heteroepitaxial systems

Supersonic molecular beam techniques have been employed to examine the dissociative adsorption of GeH4 and Si2H6 on strained Si1−xGex (0≤x≤1) epitaxial overlayers deposited on Si(100). Low-energy ion scattering spectrometry (LEISS) has been utilized to quantify in situ the topmost Ge surface composition of the Si1−xGex films. Through the measurements of reaction probability we find that these ultrathin strained semiconducting overlayers, both alloy and pure component (i.e., Ge/Si(100)), exhibit enhanced gas–surface reactivity when compared to their bulk (relaxed) counterparts, reflecting the critical role played by strain in these epitaxial overlayers.